U.N. Secretary-General Ban Ki-moon (L) and Russia's President Vladimir Putin smile as they meet at Bocharov Ruchei state residence in Black Sea resort of Sochi May 17, 2013. (POOL/REUTERS)

As Russian warships from the Pacific, Black Sea, Northern and Baltic fleets steamed toward a rendezvous in the eastern Mediterranean, U.N. Secretary General Ban Ki-moon met with Russian President Vladimir Putin on Friday to underscore his support for a peace conference on Syria proposed by Moscow and Washington earlier this month.

“The crisis in Syria is first and foremost on our minds,” Ban said at a news conference with Foreign Minister Sergei Lavrov in the Black Sea city of Sochi. “Now our challenge is to build on the momentum that Foreign Minister Lavrov and Secretary [of State John F.] Kerry have helped to generate.”

The naval task force, which now consists of 11 ships, marks the Russian navy’s first significant foray into the Mediterranean since 1992. Military analysts generally agree that it was not sent to defend the regime of Syrian President Bashar al-Assad, although one of its purposes may be to dissuade Western powers from a blockade of continuing Russian arms shipments to Syria.

Lavrov reiterated Friday that the air defense systems and other hardware, including anti-ship missiles, being delivered to Syria are not illegal and that Russia is obligated to provide them under existing contracts. The New York Times reported Friday that Russia is supplying missiles with more-sophisticated radar guidance than those it delivered two years ago.

“I do not understand why the media are trying to turn it into a sensation,” Lavrov said. “It is not a secret that we are delivering weapons to Syria, under previously signed contracts, without violating any international treaties.”

Sergei Mikheyev, an independent political analyst in Moscow, said: “There are no special deliveries — there are only deliveries in the context of the contracts concluded in the past. But we don’t know what’s in the contracts. That’s the problem.”

A Syrian opposition spokesman denounced Russia’s stance. “It’s very unfortunate that while the Free Syrian Army is practically out of ammunition for their personal weapons, the regime continues to receive advanced weapons from Russia and Iran, even while Mr. Lavrov himself calls for a political settlement,” said Najib Ghadbian, the Syrian Opposition Coalition’s representative in the United States.

“It defies logic that one side is armed to the teeth and the other is told make peace and surrender,” Ghadbian said, speaking by phone from Washington. “We hope our friends will see the need, if these talks fail, to provide military support.”

Israel has expressed fears that Assad might transfer Russian arms to the militant Lebanese Shiite group Hezbollah, but Ruslan Pukhov, director of the Center for Analysis of Strategies and Technologies in Moscow, said that none of the Russian hardware being delivered is small enough to be useful to an irregular force such as Hezbollah.

“The S-300 is not a box of matches,” he said, referring to an air defense missile. “You can’t hide it.”

Mikheyev said the issue was not of concern to Moscow. “Russia doesn’t care about Hezbollah at all,” he said. “We’re not interested.”

Israeli Prime Minister Benjamin Netanyahu, who visited Putin in Sochi on Tuesday, probably came away with a guarantee that Russia would not ship small arms to Syria, Pukhov said — although that was only part of what he was seeking.

In Washington, Defense Secretary Chuck Hagel and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said Russia’s provision of advanced anti-ship cruise missiles to Syria risks triggering a regional conflict.

“It’s, at the very least, an unfortunate decision that will embolden the regime,” Dempsey said at an afternoon news conference at the Pentagon.

The missiles, which are fired from mobile batteries on land, have more-advanced radar than similar versions in Syria’s arsenal and would probably force U.S. naval ships to remain farther off the Syrian coast in the event of hostilities. But Hagel and Dempsey said the larger risk is that Assad will think that he is somehow safer and engage in more-provocative attacks that could engulf the region in a war.

Kerry has made clear to Moscow that the administration wants Russia to stop supplying weapons to Syria. State Department spokeswoman Jen Psaki said Friday that the department was unaware of new shipments of anti-ship missiles to Syria, suggesting the versions were already in the arms pipeline.

Five ships from Russia’s Pacific Fleet entered the Mediterranean on Thursday after the long trip from Vladivostok and were to stop in Cyprus en route to a rendezvous with the rest of the task force, already in place. The exercise, Pukhov said, is primarily a way for Russia to show that it is still in the “top league” and also an opportunity for Russian sailors and officers to gain some deep-water experience.

Sergei Shoigu, the Russian defense minister, has said that Russia should reestablish a permanent naval presence in the Mediterranean to protect its interests there. Russia’s only naval base outside the former Soviet Union is in the Syrian port of Tartus, but it is not large. It is, however, in Syria’s Alawite homeland, where Assad, an Alawite, would be expected to make a last stand if his control of the rest of the country crumbles.

No date has been set for the Geneva peace conference, but Russian and U.S. officials hope to get it underway by early June.

Putin also discussed plans for the Syria conference by phone Friday with British Prime Minister David Cameron.

Caroline Anning in Beirut contributed to this report.