The international community is stepping up pressure on Russia to pull its troops out of Ukraine, but the Crimean peninsula remains under the control of Russian soldiers.
The Group of Seven major industrialized nations on Sunday condemned Moscow's invasion of Ukraine, and even cancelled preparations for an upcoming G8 summit scheduled to take place in Sochi in June.
U.S. Secretary of State John Kerry, who will arrive in Kiev on Tuesday, has condemned Russia for what he called an "incredible act of aggression," and warned that the country has a lot to lose if it presses on with its current course of action.
In an interview with NBC's "Meet the Press," Kerry sent a stronger message, saying there could ultimately be asset freezes, visa bans and implications on trade.
The U.S. Congress has already called for sanctions against Russia.
Russia's parliament has already given the green light to its President Vladmir Putin to use military force to protect its citizens in Ukraine, defying calls from the international community not to intervene.
Over the weekend, Ukraine mobilized its military for a possible confrontation with Russia, which had previously dispatched more than 6-thousand troops to Crimea.
Some surrounded several small Ukrainian military outposts, demanding forces there to disarm.
On Sunday, Ukraine's navy chief defected to Russia after having been appointed just a day before.
Russia has also been staging military exercises involving 150-thousand troops along its border with Ukraine.
Shin Se-min, Arirang News.