KIEV, Nov. 26 - Russian forces are still operating in eastern Ukraine, providing the backbone of separatist rebels fighting the Kiev government, NATO's top military commander said on Wednesday after talks with Ukrainian leaders, Reuters reported.

U.S. Air Force General Philip Breedlove, visiting Kiev as head of U.S. forces in Europe, said Russia's "militarization" of the Crimea peninsula it annexed from Ukraine in March meant Moscow could exert influence over almost the entire Black Sea region.

Breedlove met Ukrainian President Petro Poroshenko and others in the pro-Western leadership to discuss ways the United States could assist Kiev's defense potential in the conflict with Russian-backed separatists in eastern territories.

Asked for an assessment of the situation, Breedlove said Russian troops in the east were "training, equipping, giving backbone ...helping (separatist) forces in the field."

Russia denies sending troops or equipment to the rebels but accuses Kiev of using indiscriminate force against civilians in the two eastern territories of Donetsk and Luhansk.

Breedlove said Russian forces were also helping the rebels "understand the advanced weaponry that is being brought across", referring to military equipment which Kiev and the West says is being funneled into Ukraine from Russia.

He said the United States remained concerned by Russia's "militarization" of the Crimea peninsula which included possible stationing of coastal defense cruise missiles and surface-to-air missiles "that are able to exert military influence over the Black Sea."

The United States also continued to watch for indications Russia might move "nuclear capabilities" onto the peninsula in line with a Russian defense ministry announcement last March, he said.

Breedlove's visit followed that of U.S. Vice-President Joe Biden to Kiev last week at which he announced strong U.S. support for a democratic Ukraine - but made no announcement of any new non-lethal military aid.

Despite appeals by Kiev, NATO and NATO member countries have drawn the line at providing weapons to Ukraine for fear of being embroiled in a conflict with Russia on behalf of a country that is not a member of the U.S.-led alliance.

Pressed on Wednesday to say whether Washington might change its policy, he said the United States continued to look at requirements in Ukraine and "nothing at this time is off the table." (rt/ez)