BERLIN — The U.S. military estimates around 12,000 Russian soldiers are supporting pro-Moscow separatists in eastern Ukraine, U.S. Army Europe Commander Ben Hodges said on Tuesday.

The Russian forces are made up of military advisers, weapons operators and combat troops, Hodges said in a speech in Berlin, adding that a further 29,000 soldiers were stationed in the Crimea peninsula that Moscow annexed from Ukraine last year.

In addition, 50,000 troops are positioned on the Russian side of the border with Ukraine in case the separatists suffer a severe setback and the Ukrainian army gains the upper hand, Hodges said.

Russia has repeatedly denied claims that it is directing the rebel assault in eastern Ukraine with its own troops and weapons, despite what the Kiev government and Western countries say is incontrovertible evidence.