On December 19, the two governments signed a new strategic partnership deal intended to show Moscow that Washington is committed to eventual NATO membership for Ukraine.
The agreement signed in Washington by U.S. Secretary of State Condoleezza Rice and Ukrainian Foreign Minister Volodymyr Ogryzko is nonbinding, but it mentions broad areas of cooperation, including economic development and defense. It also contains promises to enhance the United States' training and equipping of Ukraine's military through NATO.
Deputy U.S. Assistant Secretary of State David Merkel said the new agreement is meant to "break Moscow's narrative that it has laid out markers saying that the direction has to be reversed, the direction of U.S. involvement has to be blunted.”
The agreement also includes a statement by Ukraine welcoming the U.S. intention to open a new "diplomatic presence" on the Crimean peninsula, the Ukrainian region where Russia's Black Sea fleet is based.
State Department spokesman Sean McCormack said the United States is "considering opening an American presence post in the Crimean capital of Simferopol to expand...exchanges and promote mutual understanding between the United States and the Crimean region."
Most of the 2 million residents of Crimea are ethnic Russians. Although Russian officials have denied claims that Moscow is a threat to Ukraine's sovereignty, its move against Georgia in August has elevated fears of a separatist movement on the peninsula.
Russia's lease on its Soviet-era naval base in Sevastopol runs out in 2017, and Ukraine says it will not be extended.
The new U.S.-Ukrainian agreement is a sign that the United States is trying to shore up Ukraine's position in the standoff.
Olexander Sushko, of Kyiv's Center for Peace, Conversion, and Foreign Policy, said the document was necessary because Ukraine is years away from becoming a member of NATO. Because the United States has lobbied so hard, without success, for Ukraine to be given a Membership Action Plan (MAP), Sushko said a new strategic partnership was the next best thing it could offer.
"This document has more of symbolic weight than any serious security guarantees, Sushko said. “The signing of the document is a reaction of two countries, Ukraine and the U.S., to a certain slow-down in the process of Ukraine's NATO integration, in the sense that in the next several years Ukraine will not become NATO member. Because of this it was necessary to demonstrate a reaction on a bilateral level, to signal that the two sides have a serious bilateral interest in each other."
For all its promises, though, the new U.S. document cannot replace the collective security guarantees that NATO offers, Sushko warns.
"It is not a substitute for a collective security treaty. For example, the U.S. has a bilateral security treaty with South Korea. It is very different in nature. It is a treaty which carries serious security commitments,” he said. “Ukraine cannot hope for the same type of 'special' relations which formed between the U.S. and South Korea as a result of the circumstances in 1940-1950s, after the war, when this treaty came to life.... We are talking about a different level of commitment and a different level of political will to protect Ukraine, using U.S. political or military might."
President George W. Bush leaves office on January 20, and State Department officials were not clear whether a decision would be made about the Crimean post before he leaves, or if it would fall to his successor, President-elect Barack Obama.
RFE/RL's Ukrainian Service contributed to this report