As Ukraine took a historic step closer to Europe, its strategic, predominately Russian-speaking province of Crimea went firmly into Moscow's grip. President Putin signed bills at the Kremlin completing its annexation.
In Brussels, Ukraine's Interim Prime Minister Arseniy Yatsenyuk explained his country only had two options to respond to Russia's moves.
"The first one is military, which is not really acceptable for the world to have the third world war," he noted. "The second one is political, diplomatic and economic. The best way to contain Russia is to impose real economic leverage over them."
The political accord between Kyiv and the EU does not immediately change anything on the ground in Ukraine. But Ukraine's Deputy Foreign Minister Danylo Lubkivsky says the pact puts Ukraine on a new path to tackle the host of problems it faces.
"We are doing an enormous piece of work right now -- having the Crimea conflict, having the economy in a very bad situation, having all those corruption and ill problems that are the heritage of the previous rule," he said.
Adding to those concerns, Moscow is asserting Kyiv owes it billions of dollars for past natural gas deliveries, and has warned it could reconsider the discount for natural gas that Russian President Vladimir Putin promised late last year to ousted Ukrainian leader Viktor Yanukovych. Moscow has cut natural gas deliveries to Ukraine several times in the last decade.
U.S. Special Envoy on Energy, Carlos Pascual (a former ambassador to Ukraine) is in Kyiv to talk with government leaders about the country's energy security. He says Ukraine could be gas self-reliant by 2020.
The ambassador expressed hope Russia will continue to want to utilize the transit system through Ukraine.
"And in order to be able to satisfy the demands of its customers throughout central Europe, throughout Western Europe, Russia has an opportunity to be able to utilize the supply routes that exist and to continue to supply gas that would also come to Ukraine," he said.
After a stop in Moscow, United Nations Secretary-General Ban Ki-moon arrived in Kyiv to meet with top officials of the interim government. He immediately expressed concern about the possibility of the crisis expanding beyond the region.
"This current crisis can only be resolved through peaceful diplomatic solutions based on the principles of the United Nations Charter, including respect for the sovereignty, unity and territorial integrity of Ukraine, and a determined statesmanlike pursuit of peace and security," Ban said. "There has to be a real dialogue between Kyiv and Moscow."
Ihor Smeshko, a former head of Ukraine's intelligence service who was a colonel in the Soviet army, said if Ukraine’s military and reserves are not mobilized for defense, that will be interpreted as a lack of will to protect the country's sovereignty.
"If we will not show for the whole world and for Ukrainian people that this government and this country is prepared to defend themselves it would be the hugest provocation to our former strategic partner [Russia] and now the main strategic opponent to go further," Smeshko said.
Meanwhile, U.S. Ambassador Stephen Mull in Warsaw reiterated to reporters the American and Polish governments are discussing expanding aviation detachment exercises to include forces from the Baltics, Bulgaria, the Czech Republic, Hungary, Slovakia and Romania.