MOSCOW (AP) - President Vladimir Putin on Wednesday ordered massive exercises involving most of its military units in western Russia amid tensions in Ukraine.

Defense Minister Sergei Shoigu said in a televised statement made at a meeting of top military brass in Moscow that the exercise is intended to "checks the troops' readiness for action in crisis situations that threaten the nation's military security."

Shoigu said Putin ordered the exercise Wednesday afternoon. During the first two days, the military will be put on high alert and some will deploy to shooting ranges.

The actual maneuvers will start Friday and will last four days, he said. The exercise will involve ships of the Baltic and the Northern Fleets and the air force.

Shoigu's statement didn't contain any reference to Ukraine, where tensions remain high following the toppling of Russia-backed President Viktor Yanukovych. Russia has questioned the legitimacy of the new Ukrainian authorities and accused them of failing to control radicals who threaten the Russia-speaking population in Ukraine's east and south.

A senior Russian lawmaker on Tuesday told pro-Russia activists in Ukraine's Crimean Peninsula where Russia has a major naval base that Moscow will protect them if their lives are in danger.