U.S. Secretary of State John Kerry said Thursday he has been assured by Russia that it will respect the sovereignty of Ukraine and that military exercises near its borders are not a prelude to military invention by Moscow.

Kerry said he spoke with Russian Foreign Minister Sergey Lavrov, who said the massive buildup of troops, aircraft and naval ships was previously scheduled and is not related to the recent unrest in Ukraine.

The military movements had unnerved the U.S. because it followed the overthrow of Ukraine's pro-Russia President Viktor Yanukovych, who has fled the capital Kiev, and is reportedly seeking refuge outside Moscow. Earlier this week, Kerry warned Russia against a military intervention in Ukraine, a former Soviet republic, and said it could face a strong but unspecified response from the West.

At a news conference Thursday with German Foreign Minister Frank-Walter Steinmeier, Kerry said he would continue to watch Russia's actions to ensure they match Moscow's words.

"Everybody needs to step back and avoid provocations," Kerry said.

He added: "Words are words. We have all learned that it's actions and the follow-on choices that make the greatest difference."

Kerry said the U.S. also supports a vote Thursday by Ukraine's parliament to approve a transitional government in Kiev that will run the country until elections can be held in May.

In a statement issued before the news conference, Steinmeier said it's important for Kiev's new leaders to "show that it is a government for all Ukrainians and that it now works together with international institutions, and with its neighbors, to stabilize the country financially."

"East and West should not argue now about Ukraine's future," he said.

Steinmeier, who was on a trip to Washington, welcomed a move by the International Monetary Fund to send a fact-finding team and said he will discuss with IMF chief Christine Lagarde Friday what the financial institution can do in terms of providing immediate aid. He underlined the EU's and America's readiness to help and said "we are talking with Russia about help pledged to Ukraine not being withdrawn or canceled. If the four partners came together on the necessary financial stabilization, that would be a good point of departure."

At the White House, press secretary Jay Carney welcomed the efforts by Ukraine's parliament to stabilize the country, and said Yanukovych "abdicated his responsibility."

Carney also said Yanukovych left a "void" that Ukraine's lawmakers are trying to fill.

A respected Russian news organization reported that Yanukovych was staying in a Kremlin sanitorium just outside Moscow, and he was said to still consider himself president.

Carney said the U.S. expects the interim government to protect the security and civil rights of all of citizens in Ukraine, which has a large Russian-speaking population.