As Crimea grew more militarized and isolated Tuesday and hopes for a diplomatic solution to the Ukraine crisis looked increasingly faint, European nations said they were preparing to punish Russia with sanctions within days.

European officials met in London to draw up penalties against Russia, likely to include asset freezes and travel bans, unless the country accepts a U.S. proposal to stop its expansion in Crimea and start discussions with Ukraine’s new government. Until now, Western efforts to curb Russia’s actions have focused on rhetoric and largely symbolic gestures, rather than measures that would cause meaningful pain in Moscow.

The European restrictions could mark a substantial escalation in a conflict that has pitted Russia against the West in a way not seen since the Cold War. But the Obama administration has refused to set a deadline for U.S. sanctions or indicate a specific Russian action that would trigger them. And analysts say that even tough sanctions are unlikely to force Russian President Vladimir Putin to change course in Ukraine, given the depth of Russian interests there.

“For the Kremlin, and the wider elites that support it, the fate of Ukraine is a vital interest. They’ve tied Ukraine’s future to their own,” said James Sherr, an associate fellow at the London-based think tank Chatham House. “Any sanctions the E.U. is likely to come up with will not be sufficient to change that calculation.”

In Washington, State Department spokeswoman Jen Psaki said the Treasury Department is working on an escalating set of measures that allow the United States to “calibrate sanctions and other actions depending on the steps that Russia takes.”

She added that Russia had replied to a list of U.S. requirements and suggestions to ease tension, but she said the response duplicated positions Moscow took last week during meetings between Secretary of State John F. Kerry and Russian Foreign Minister Sergei Lavrov.

While diplomatic efforts floundered, the situation in Ukraine continued to change swiftly. As the regional Crimean parliament approved a declaration of independence, the government in Kiev established a new national guard and acknowledged that the nation’s armed forces were hardly up to a fight with Russia.

Acting President Oleksandr Turchynov said Ukraine would have to rebuild its military “effectively from scratch.” The pro-Western leader said it has only 6,000 combat-ready infantry, compared with 200,000 Russian troops on Ukraine’s eastern border.

Meanwhile, Russian soldiers and the paramilitary “self-defense” units under the command of the Russian military continued their step-by-step takeover of Crimea. On Tuesday, they were in control and standing guard at several military bases, with Ukrainian troops cornered inside.

In the regional capital, Simferopol, witnesses reported that pro-Russian forces had taken over the prosecutor’s office and the railway administration. At the civilian airport, all Istanbul and Kiev flights were canceled, leaving only flights to and from Moscow in operation.

Several urban military facilities in Simferopol are surrounded by sandbags and land mines. Pro-
Russian troops patrolled outside the airport and were stationed inside official buildings.

Government officials reached by telephone said armed men had entered their workplaces forcibly, taken away their phones and rifled through their documents. They said that they were not told to leave but that armed men remained stationed in the corridors.

Still, in the city centers life went on largely unimpeded, with few signs of a military buildup. But ahead of a Sunday referendum on whether Crimea should remain in Ukraine or become part of Russia, billboards and posters popped up for what has become a one-sided campaign. The signs, all favoring Russia, boiled down the choice to one between being annexed to Russia or enduring fascism and Nazism by staying in Ukraine.

One billboard showed two maps of Crimea: one adorned with a swastika, the other with the tricolor stripes of the Russian flag. Another showed the acronym NATO with an X drawn over it in a way that suggests a vulgarity in Russian.

Crimean authorities are moving apace as if the referendum had already taken place. On Tuesday, the regional parliament voted to declare Crimea an independent state, a move evidently aimed at legally smoothing the way for the region’s annexation to Russia.

The 78 to 3 parliament vote was denounced by human rights and opposition activists, who have urged a boycott of the referendum.

Alex Mnatsakanian, a Moscow-based human rights activist now working in Simferopol, described pro-Russian Crimean leaders as a “locomotive” trying to rush through annexation under a thin cover of legislative decrees with no legal standing.

“They are trying to make a trick that will stop the world from blaming Russia,” Mnatsakanian said. “But if they are trying to put a good face on it, this is impossible with all the Russian forces who are everywhere in Crimea now. It is just a circus.”

Another perspective was offered by deposed Ukrainian president Viktor Yanukovych, who said Tuesday that a junta in Kiev had provoked Crimea to secede by spreading lawlessness and refusing to protect civilians from violence.

Yanukovych, speaking at a shopping center in the Russian city of Rostov-on-Don, accused the West and the United States of backing fascists in Ukraine, an allegation regularly made by Russian authorities.

“There is a gang of ultranationalists and fascists operating the government,” he said. “I would like to ask those who cover for these dark forces in the West: Are you blind? Have you forgotten what fascism is?”

Yanukovych railed against the United States for offering $1 billion in aid to the new Ukrainian government and said he intended to ask the U.S. Congress and the U.S. Supreme Court to investigate the legality of such a move.

The Russian Foreign Ministry also cited U.S. law, specifically the Foreign Assistance Act of 1961.

U.S. financial aid to the government of a country whose legitimately elected president has been overthrown as a result of a military coup or an unlawful decision is illegal, a ministry statement said. But the section of U.S. code that the statement cited referred specifically to U.S. aid to Pakistan, not Ukraine or any other country.

Meanwhile, Ukraine’s interim prime minister, Arseniy Yatsenyuk, who is scheduled to meet with President Obama in Washington on Wednesday, called on Western nations to defend Ukraine against Russia. He called Russia a nation “that is armed to the teeth and that has nuclear weapons.”

Constable reported from Simferopol. Kathy Lally and Will Englund in Moscow, Griff Witte in London, and Anne Gearan and Karen DeYoung in Washington contributed to this report.