The US troops from 173rd Airborne Brigade arrived this week to Yavoiv in western Ukraine to train three battalions of Ukrainian soldiers, the US Army said Thursday.

"We will be conducting classes on war-fighting functions, as well as training to sustain and increase the professionalism and proficiency of military staffs," Maj. Jose Mendez, operations officer for Italian based paratrooper brigade, said in the statement.

The training for 900 National Guard soldiers is set to last six months, with the Ukrainian and American troops conducting joint exercises. Ukrainian National guard is a reservist force predominately out of former Maidan-movement participants and under command of Ukraine Interior Ministry.

The information has been confirmed on Friday by the American ambassador in Kyiv, Geoffrey Pyatt.

The US government has supplied Ukrainian troops with military equipment including armored vehicles, bullet-proof vests, radars and night-vision goggles.

Washington has so far abstained from supplying weapons to Kyiv forces.

Rebels claim Kyiv is preparing an offensive

Moscow warned on Friday that presence of foreign military personnel could further destabilize the situation in Ukraine.

"The participation of instructors and experts from third countries on Ukrainian territory, ... of course, does not help to resolve the conflict," President Vladimir Putin's spokesman Dmitry Peskov said.

Moscow has in the past accused the United States of backing the protesters who ousted the pro-Russian former President Viktor Yanukovych last year.

The West in turn accuses Kremlin of arming and supporting the rebels in the east of the country. In a televised question-and-answer session on Thursday, Russian President Vladimir Putin said Moscow had not sent any Russian troops to Ukraine.

Over 6,000 people have died since the beginning of the Ukrainian conflict, according to the United Nations, and tensions in the country's east remain high despite a shaky ceasefire.

dj/sms (AP, Interfax, dpa, AFP)