A Russian infantry battalion pulls back from near Ukraine's eastern border on Monday.

Moscow says the military build-up in this area is part of military exercises and that there are no plans to move its forces from the border and into Ukraine.

The U.S. and NATO are not so sure.

They've sounded the alarm over Moscow's intentions, following its annexation of Crimea from Ukraine earlier this month.

But as a battalion pulls out, tanks move in.

Russian military hardware started to arrive in Crimea on Monday.

Russia's Deputy Defense Minister said Russia is re-equipping Crimea's military.

Taking away Ukrainian hardware and replacing it with that of the Russian army.

(SOUNDBITE) (Russian) RUSSIAN DEPUTY DEFENSE MINISTER, ARMY GENERAL DMITRY BULGAKOV, SAYING:

"Today, the first trains have left. Tomorrow, they will be followed by the others. Today, we will put together the schedule and finish the whole operation within a month."

Russia