WASHINGTON, Feb. 26 - The United States warned Russia on Wednesday it would be a "grave mistake" to intervene militarily in Ukraine and said it was considering $1 billion in U.S. loan guarantees and additional funding to help Kiev.

U.S. Secretary of State John Kerry issued the warning after Russian President Vladimir Putin put 150,000 combat troops on high alert for war games near Ukraine, Moscow's boldest gesture since the ouster of ally Viktor Yanukovych as president in Kiev, Reuters reported.

"For a country that has spoken out so frequently ... against foreign intervention in Libya, in Syria, and elsewhere, it would be important for them to heed those warnings as they think about options in the sovereign nation of Ukraine," Kerry told a small group of reporters at the U.S. State Department.

The war games will involve some 150,000 troops, 880 tanks, 90 aircraft and 80 navy ships, and are intended to "check the troops' readiness for action in crisis situations that threaten the nation's military security," Defense Minister Sergei Shoigu said in remarks carried by Russian news agencies.

Kerry said: "I don't think there should be any doubt whatsoever that any kind of military intervention that would violate the sovereign territorial integrity of Ukraine would be a huge - a grave mistake," he added.

"If there were any kind of decision like that, I do not think that's a cheap decision. I think it's a very expensive decision."

Kerry said Washington was considering $1 billion in U.S. loan guarantees for Ukraine, as well as possible budget support for the former Soviet republic, but said no decisions had been made. He said Europe was also mulling roughly $1.5 billion in assistance to Ukraine.

"We are formulating initially a $1 billion loan guarantee with some other pieces, but we are also looking at the possibility of additional assistance," Kerry said.
The Obama administration was discussing the matter internally, he said.

"I don't think it's enough to be heralding the advent of democracy and applaud the courage and conviction of the people who brought about this transition and then just not do anything. I think that is unconscionable," he added.

State Department spokeswoman Jen Psaki later said the United States was prepared to take immediate steps to help Ukraine's economy after a new government was formed and in coordination with a lending program from the International Monetary Fund, the global financial institution.

Ukraine fell into political crisis last year when Yanukovych spurned a broad trade deal with the European Union and accepted a $15 billion Russian bailout that is now in question.

After weeks of popular protests and clashes between security forces and demonstrators, Yanukovych fled his Kiev office and Ukraine's parliament voted to remove him from power on Friday.

With Kiev desperate for cash as it charts a new future, U.S. officials have emphasized that any U.S. funding would complement an IMF program, which would offer oversight of economic reforms and ensure money is being spent properly.

IMF officials told Reuters this week that one option under review to help prop up Ukraine's ailing economy was a bailout that would include IMF money as well as bilateral loans and guarantees from the U.S. and other governments. (rt/ez)