The US Navy is sending a guided missile cruiser to the Black Sea, the Pentagon said Tuesday, the latest bid by Washington to to reassure allies worried over Russia's intervention in Ukraine.

"I can confirm the Vella Gulf, a Navy cruiser, will be going in to the Black Sea probably later this week," Pentagon spokesman Rear Admiral John Kirby told reporters.

The Vella Gulf will arrive in the Black Sea after the recent departure of the frigate USS Taylor, which left the area on May 12.

Since the crisis in Ukraine began in March, the United States has deployed troops to Eastern European countries for joint drills and sent ships to the Black Sea for exercises with NATO states in the area.

But the 1936 Montreux Convention that governs the Black Sea bars outside countries from keeping warships in the strategic waters more than 21 days.

The Pentagon, keen to allay the concerns of allies bordering Russia, has said it would keep up regular deployments of troops to NATO members in Eastern Europe through the end of the year.

The higher US military profile also would "include naval presence in and out of the Black Sea," according to Kirby.

He also said there was no sign of a Russian withdrawal of troops from the Ukrainian border, despite an announcement of a pullout from Moscow.

"They are still in the tens of thousands," Kirby said. "We have not seen any withdrawal activity," he said.

Ukraine said earlier that Russian troops had moved away from the border, but stopped short of confirming a full withdrawal as demanded by the West.

Ukraine's border service issued a surprise announcement early Tuesday that none of the estimated 40,000 Russian soldiers were now stationed within 10 kilometers (six miles) of the country.

NATO still sees no sign of Russian Ukraine troop pullback
Brussels (AFP) May 20, 2014 - NATO said Tuesday there was still no sign that Russian forces were being withdrawn from the Ukraine border after President Vladimir Putin announced a return to their bases.

"We have not seen a change at the border," a NATO official said when asked if there had been any developments subsequent to Putin's announcement Monday.

NATO head Anders Fogh Rasmussen said Monday that after what he believed to be the Russian president's third such statement, "unfortunately, we have not seen any evidence at all that Russia has started withdrawal."

NATO has estimated there are some 40,000 Russian troops on the border, whose presence has raised fears they may intervene in troubled eastern Ukraine after Moscow's annexation of Crimea in March.

A pullback could ease spiralling tensions five days ahead of a key presidential poll on Sunday.

Ukrainian Foreign Minister Andriy Deshchytsia said earlier Tuesday that his government could not yet confirm Russia's claim it had pulled its troops back from his country's border.

"We hope that the declarations by Russian politicians that the troops are to be withdrawn from Ukraine's borders don't just remain declarations," he said in Berlin.

Ukraine border guards said earlier that Russian forces had left an area within 10 kilometres (six miles) of the frontier following Putin's statement in which he also called on Kiev to halt military operations against pro-Kremlin rebels in the country's east.

Russia's defence ministry said Tuesday troops were still preparing their departure.

"The men have started dismantling their tent camps, loading equipment and forming columns of vehicles and armour," the ministry told Interfax news agency.