Congress is imposing harsher sanctions on Russia over its annexation of the Crimean Peninsula.
The decision comes as the U.N. General Assembly approved a resolution Thursday declaring Russia's annexation of Crimea as illegal.
Meanwhile, Ukraine's prime minister is making an appeal for military support from the international community.
"We need technical and military support to overhaul the Ukrainian military, to modernize it, and to be ready not just to fight but be ready to win," Ukraine Prime Minister Arseniy Yatsenyuk said.
Last week, the United States and the European Union imposed travel bans and asset freezes on two dozen Russian officials.
Now Moscow says it will set up its own payment system after VISA and Mastercard pulled their services from some Russian banks.
Despite growing international pressure, Russian aggression appears to be increasing. Moscow's military continues to send soldiers to Ukraine's border, including Russian Special Forces.
U.S. and European security agencies estimate Russia has deployed more than 30,000 troops. Many of them are wearing undercover uniforms similar to those Russian forces wore as they moved in to seize Crimea.
Speaking in Brussels Wednesday, President Barack Obama said Ukraine's crisis cannot be resolved with force. But he also pledged that NATO countries sitting nervously on Russia's border will be defended at any cost.
"In that promise, we will never waver. NATO nations never stand alone," Obama said.
"Russia's leadership is challenging truths that only a few weeks ago seemed self-evident: that in the 21st century, the borders of Europe cannot be re-drawn with force; that international law matters," he said.
Meanwhile, the International Monetary Fund said it's prepared to loan Ukraine from $14 billion to $18 billion.