As Secretary of State John F. Kerry met with his Russian counterpart in Paris, a standoff continued Wednesday between Russia and Ukraine over Crimea, and a U.N. envoy was forced to abandon a mission to the region after encounters with pro-Russia militiamen and an angry crowd.

Kerry met with Russian Foreign Minister Sergei Lavrov, the foreign ministers of Britain, Germany and France, and French President Francois Hollande in Paris an effort to resolve the Ukrainian crisis. But Russia rebuffed the demands of the United States and its allies that Russia pull its forces in Crimea back to their bases, news agencies reported.

The diplomacy went ahead as Russian and Ukrainian warships faced off in this Crimean port with no sign of a breakthrough in a stalemate between the new government in Kiev and pro-Russian authorities in the Crimean Peninsula.

In Brussels, the European Union weighed in Wednesday with a proposal to provide a $15 billion aid package of loans and grants to Ukraine in the coming years, on top of a U.S. announcement Tuesday of $1 billion in loan guarantees.

And NATO announced Wednesday that it is suspending collaboration with Russia on several fronts, including planning for the first joint NATO-Russian mission, as part of an effort to “de-escalate tensions” in Ukraine.

The E.U. package is “designed to assist a committed, inclusive and reforms oriented Government in rebuilding a stable and prosperous future for Ukraine,” European Commission President Jose Manuel Barroso said in a statement. The package would be phased over several years, but Barroso did not immediately specify any conditions that Ukraine would have to meet in overhauling its economy. Kiev estimates it needs $35 billion in international rescue loans over the next two years.

The package is to be formally approved Thursday, perhaps along with sanctions on Russia. It includes about $8 billion in loans and grants spread over several years and further assistance from the European Investment Bank.

In Simferopol, the capital of Ukraine’s autonomous Crimea region, U.N. special envoy Robert H. Serry was accosted Wednesday by unidentified armed men after visiting a naval headquarters in the city, U.N. Deputy Secretary General Jan Eliasson told reporters by telephone from Kiev. Eliasson said the group of 10 to 15 men blocked the Dutch diplomat’s car and ordered him to go to the airport and leave Crimea immediately.

“He refused,” Eliasson said, and left the vehicle on foot to walk back to his hotel. Eliasson called the incident “very regrettable” but said Serry told him by phone from a coffee shop that he is “in good shape physically” and was “not kidnapped.”

A reporter from Britain’s ITV News, who was accompanying Serry, said local pro-Russia militiamen in combat fatigues subsequently blocked the door to the coffee shop with the U.N. envoy inside. Reporter James Mates said Serry agreed to end his mission and go straight to the airport. Serry then got into a car for the drive to the airport as an angry crowd chanted slogans in support of Russia and President Vladi­mir Putin. Serry said he was happy to leave Crimea if it helped to de-escalate the situation, Mates wrote on his Twitter feed.

NATO’s decision to suspend collaboration with Russia affects a joint mission in which Russia was to provide a maritime escort for the U.S. container ship Cape Ray, aboard which Syrian chemical weapons are to be destroyed at sea. In addition, the alliance has canceled all staff-level civilian and military meetings with Russia, and “we have put the entire range of NATO-U.S. Russia cooperation under review” pending a meeting of NATO foreign ministers in April, NATO Secretary General Anders Fogh Rasmussen said.

The announcement came after a meeting in Brussels of the NATO-Russia Council, established in 2002 to facilitate cooperation. The alliance suspended council activities in 2008 to protest Russia’s invasion of Georgia, a former Soviet republic that gained independence in 1991. Although Russian troops remain in breakaway regions of Georgia, NATO decided to fully resume council activities in early 2009.

Rasmussen described Wednesday’s measures as a balance between sending a “clear message” to Russia and keeping “a channel open for political dialogue.” He said NATO’s actions were being coordinated with those taken by other international organizations and that together they would “send a very clear message to Russia that they must de-escalate tensions” in Ukraine. He said suspension of Russian participation in the Syrian operation would not impede destruction of the chemical weapons.

In Crimea, meanwhile, the newly appointed pro-Russian regional prime minister, whose own legitimacy has been questioned because he was installed after masked gunmen seized the Crimean parliament, said his administration was not speaking with the national government in Kiev.

“We don’t consider this government that proposes talks to us to be legitimate; that is the main issue,” Crimean Premier Sergei Aksyonov told a Latvian radio station.

[READ: How Ukraine got where it is today, in 486 words.]

Russian officials continued to deny that their forces were spread out across the Crimean Peninsula. Russian Foreign Minister Lavrov, speaking in Madrid, said Wednesday that all the armed men who arrive in Russian troop transports, with Russian plates, are local self-defense militias.

In Moscow, Russian Defense Minister Sergei Shoigu denied Wednesday that any of his troops had strayed from their bases in Crimea despite videos and photos that suggested otherwise.

“No, absolutely not,” he responded when asked by Kremlin pool reporters if there were any Russian troops in Crimea outside their own bases.

Even though videos show troops in Crimea admitting they are Russian, despite wearing uniforms without any insignia, Shoigu echoed statements made Tuesday by Putin, who insisted the troops were exceptionally well-trained Crimean self-defense units.

“Of course, these are provocations,” Shoigu said, regarding the videos. When asked how Crimean self-defense troops could have come into possession of Russian Tiger and Lynx armored vehicles, he said he had no idea, the Interfax news agency reported.

On Tuesday, Kerry dismissed Russian denials that its troops were surrounding Ukrainian military bases.

“The contrast really could not be clearer: determined Ukrainians demonstrating strength through unity, and the Russian government out of excuses, hiding its hand behind falsehoods, intimidation and provocations,” Kerry said during a visit to Kiev.

[READ: Russian claims about Ukraine veer from reality.]

French Foreign Minister Laurent Fabius said Wednesday that economic sanctions against Russia will be discussed by the European Union when its leaders meet on Thursday. “We cannot accept, we members of the international community, a country that invades another,” Fabius said on his twitter account.

The European Union will consider sanctions against Russia if there is no de-escalation in the Ukraine crisis, he said via Twitter.

Meanwhile, the United States and Britain maneuvered to begin a diplomatic outreach to Russia. Kerry and British Foreign Secretary William Hague invited Lavrov to a meeting Wednesday morning in Paris with Ukraine’s acting foreign minister.

The Russian did not attend that meeting, although he met later with Kerry, the three European foreign ministers and Hollande.

“Regrettably missing one member,” Kerry said at the start of the session of nations that signed a 1994 agreement for post-Soviet Ukraine to give up its nuclear weapons.

Hague told reporters Wednesday that many foreign ministers gathered in Paris for an unrelated meeting on Lebanon were urging Lavrov to sit down with the Ukrainian diplomat.

The goal is to “bring the Russians into a diplomatic process,” Hague said, “at least a start of it.”

Ukraine’s acting foreign minister, Andrii Deshchytsia, traveled to Paris on Kerry’s plane from Kiev in hopes of beginning diplomatic talks that the United States and Britain see as a way for Russia to back away from confrontation.

Speaking to reporters at his country home west of Moscow on Tuesday, Putin offered a vigorous defense of his Russia’s intervention in Ukraine. He said the pro-Russian former government in Kiev was illegally overthrown last month and that the man he regards as Ukraine’s legitimate president asked him for military help.

In his first public comments about the crisis since President Viktor Yanukovych was deposed Feb. 22, Putin described Ukraine as lawless and suggested that Ukrainians appeared unable to run their own country. He said masked militants were “roaming the streets of Kiev” — even though the Ukrainian capital has remained calm in recent days.

Other Russian officials quickly imitated the pugnacious tone that Putin struck Tuesday. A member of the upper house of parliament, Andrei Klishas, said Wednesday that he planned to draft a bill that would permit Russia to confiscate property and accounts belonging to European and American companies if the West pursued sanctions against Russia.

“Any sanctions must be mutual,” he said.

Valentina Matviyenko, the speaker of the upper house, disputed the idea that the West would act against Russia. Europe depends too much on exports to Russia to risk sanctions, she said.

“Are they going to stop supplying these products to us now?” she asked reporters. “To whom are they going to supply them then? Everyone who talks about sanctions should calm down and stop talking to Russia in the language of ultimatums.”

After days of heightening tension, Putin’s remarks appeared to suggest that Russia could refrain from escalation — if Ukraine gets its house in order. Hours later, Russia proclaimed the successful test launch of an intercontinental ballistic missile in Asia, a move unrelated to the crisis but a demonstration to Ukraine and the West of Russia’s military prowess.

Putin said that so far he has not found it necessary to send troops to Ukraine but that Russia had fortified security at its installations in Crimea, where its Black Sea Fleet is based. He did not mention the Russian troops and naval forces that have surrounded Ukrainian bases and ships in Crimea.

President Obama and Kerry rejected Putin’s assertions Tuesday, with Kerry charging during a visit to Kiev that “Russia has been working hard to create a pretext for being able to invade further.”

They said that despite Putin’s claims, it was not true that Russia needs to send in troops to safeguard Russians or Russian speakers in Ukraine from violent reprisals.

Dismissing Moscow’s purported concerns, Obama said Russia was “seeking through force to exert influence on a neighboring country.”

Putin, however, accused the United States of engineering Ukraine’s troubles, suggesting that it was using Ukrainians as guinea pigs in some kind of misguided experiment.

“They sit there across the pond as if in a lab running all kinds of experiments on the rats,” he told a small group of reporters in a nationally televised meeting at his country house outside Moscow. “Why would they do it? No one can explain it.”

In Kiev, his remarks were greeted with less ferocity than might have been expected. The new government is under enormous pressure from the Russian intervention and from unrest in eastern cities, coupled with a financial crisis. It is treading carefully. As Crimea slipped further into Russian control Tuesday, Ukrainian military units there stood their ground but were careful not to provoke a conflict.

In Ukraine’s parliament, there was talk of finding a way to give Crimea more autonomy if it agrees to remain a part of Ukraine. The region has scheduled a March 30 referendum on independence or accession to Russia, although Aksyonov, Crimea’s new leader, said Tuesday that he wants to hold the vote sooner. Kerry, echoing the views of many in Kiev, said Russia had installed Aksyonov in a hurried and rigged selection process last week.

Oleh Tiahnybok, the head of the nationalist All-Ukrainian Union “Svoboda” party, said, “The Kremlin is attempting to use blackmail to solve its strategic plans. Ukraine should not succumb to it.”

And Russia’s intervention, he declared, is a failure: “Ukrainians are not running with outstretched arms toward the occupiers.”

A bloodless confrontation

It has been, all around, an unusual confrontation. After a week of deadly fighting in the streets of Kiev led to Yanu­kovych’s overthrow, the Russian takeover of Crimea has been swift yet bloodless. The atmosphere in Kiev is hardly that of a capital dealing with an intervention by a powerful neighbor.

Aksyonov said Tuesday that most of the Ukrainian military forces in Crimea have sworn allegiance to his new regional government. Officials in Kiev said that is not true.

Young men in Ukrainian self-defense groups said Tuesday that they are ready to take on the Russians but do not need to join the national army to do so.

In a stately hall that normally houses an association for architects, a militia had stashed construction hard hats and bicycle helmets atop a stairway, ready to be grabbed if things turn violent. The marble floors were lined with mattresses and sleeping bags.

“I’m ready to fight the Russians,” said Vitaliy Vovk, 24, an event planner and the militia commander. “But I’m hoping there will be no war, that it’s just Putin flexing his muscles.”

Putin’s defense

Putin said the whole operation is a friendly one, designed to help out a fraternal nation. But he described Ukraine as deeply troubled, telling his interviewers that corruption and social stratification there are even worse than in Russia.

“Out there, they are beyond anything we can imagine,” he said. “This revolutionary situation has been brewing for a long time.”

So it’s understandable why the protesters on the Maidan, Kiev’s Independence Square, wanted an uprising, he said. But they went about it the wrong way, he said, and now Ukraine has swapped one “set of thieves” — Yanukovych’s — for another, a reference to the present government.

Putin said that if he decides to send in the Russian military, he would have legal grounds to do so. Russia has displayed a letter from the ousted president asking for military help in suppressing the revolt. The current government is illegitimate, Russia contends, because Yanukovych was not properly removed from power in a formal impeachment.

“What is our biggest concern?” Putin asked. “We see the rampage of reactionary forces, nationalist and anti-Semitic forces going on in certain parts of Ukraine, including Kiev.”

“We understand what worries the citizens of Ukraine, both Russian and Ukrainian, and the Russian-­speaking population in the eastern and southern regions of Ukraine,” he said. “It is this uncontrolled crime that worries them. Therefore, if we see such uncontrolled crime spreading to the eastern regions of the country, and if the people ask us for help, while we already have the official request from the legitimate president, we retain the right to use all available means to protect those people. We believe this would be absolutely legitimate.”

Yet, the Russian government and the interim Ukrainian government have been in contact. “I’d say that they are quite sluggish, but the first steps have been taken,” Ukrainian Prime Minister Arseniy Yatsenyuk said. Consultations have been held on the ministerial level.

“Ukraine is ready to build a new style of relations with the Russian Federation,” Yatsenyuk said, based on Russia’s respect for Ukraine’s right to determine its own policies.

Lally reported from Moscow. Karen DeYoung and William Branigin in Washington and Anne Gearan in Paris contributed to this report.