普京命令俄军进入高度戒备状态

Russian Resident Vladimir Putin has ordered a massive training exercise for military units across Russia, including along the border with Ukraine.

However, Russian Defence Minister Sergei Shoigu contends the drill is unrelated to what's happening in Ukraine.

"The head of the armed forces has assigned a task to review the combat preparedness of the troops for action in case of resolving crisis situations threatening the military security of our country, as well as situations of anti-terrorist, epidemiological and technogenetic character."

But at the same time, Shoigu notes Russia is "carefully watching what is happening in Crimea".

Meanwhile, NATO defence ministers have issued a new statement supporting "Ukrainian sovereignty and independence."

NATO Secretary General Anders Fogh Rasmussen.

"Ukraine is a close and long standing partner to NATO, and NATO is a sincere friend of Ukraine. We stand ready to continue assisting Ukraine in its democratic reforms."

The United States has also released a statement, warning any military intervention into Ukraine will be met with a strong response.

US State Department spokesperson Jen Psaki.

"It's not just the Secretary who feels that would be a detrimental step to Ukraine and that would be a mistake, but it is also, you probably have seen, or let me point out to you, the statement by NATO defence ministers today, that was very strong, about the risk of military intervention in a political case like this."

The tensions come as Ukraine remains split along an east-west axis, with those in the European-leaning west supporting this weekend changes in the government.

Those in the Russian-leaning east of Ukraine have been protesting the ouster of former President Viktor Yanukovych.