More than 40,000 russian troops are deployed near the borders with Ukraine 2903144.

Defence & Security News - Russia

The Russian deployments included the establishment of supply lines and the fielding of a wide range of military forces, according to an anonymous U.S. officials.

These include militia or special forces units made up of Russian fighters wearing uniforms lacking insignia or other identifying markings, similar to the first Russian forces to move into Crimea during Russia's recent military takeover there, according to U.S. and European sources familiar with official reporting.

Russia has moved 40,000 of its troops into place on its 2,000 km border with East Ukraine. Russian President Vladimir Putin says it's nothing more than a training exercise, but Western leaders say he may be preparing to invade the eastern half of Ukraine.

In the two weeks since Crimeans voted in what the West calls a sham referendum to secede, Ukraine has been frantically trying to build up its defenses. Friday, Ukrainian troops dug trenches and built tank fortifications on the border.

President Obama has said repeatedly that the United States does not intend to respond militarily to Russia's aggression, but that may not exclude indirect assistance to Ukraine. Ukraine could seek military advice on developing a defensive strategy from the United States, NATO or other Western military experts.

Obama told CBS News that the decision by the Russian president, Vladimir Putin, to assemble forces on the border may "simply be an effort to intimidate Ukraine, or it may be that they've got additional plans".