In a diplomatic dig at Russia, President Barack Obama is hosting the new Ukrainian prime minister at the White House, a high-profile gesture aimed at cementing the West's allegiance to Ukraine's fledgling government.
The meeting Wednesday between Obama and Prime Minister Arseniy Yatsenyuk comes as a pro-Russian area of Ukraine readies for a referendum Sunday to determine its future. Voters in the Crimean Peninsula will be given two options: becoming part of Russia, or remaining in Ukraine with broader powers.
Ahead of the meeting, the U.S. and the other nations in the Group of Seven released a joint statement declaring that they would not recognize the results of the referendum.
"We call on the Russian Federation to immediately halt actions supporting a referendum on the territory of Crimea regarding its status, in direct violation of the constitution of Ukraine," the statement read. "Any such referendum would have no legal effect."
The dispute over the future of the former Soviet republic has conjured up echoes of the Cold War tensions between East and West.
Amid the symbolism of Yatsenyuk's visit to the U.S., the Ukrainian leader will also be seeking financial assistance from Washington. Yatsenyuk says his country needs the West's help to defend itself against neighboring Russia, a nation he said is "armed to the teeth."
Ukraine's parliament installed Yatsenyuk as head of the country's interim government after pro-Kremlin President Viktor Yanukovych fled the capital of Kiev following three months of popular protests. The uprising started when Yanukovych rejected a planned partnership agreement with the European Union in favor of historical ties with Moscow.
Days after Yanukovych left Kiev, Russia moved military forces into Crimea, defying warnings from the U.S. Russian President Vladimir Putin has so far brushed aside punishments levied by the West following the incursion, including visa bans, the threat of economic sanctions and a halt to planning for an international economic summit Russia is scheduled to host in June.
The Senate Foreign Relations Committee planned to vote Wednesday on a package of economic penalties targeting Russian officials complicit in Ukrainian corruption or anyone responsible for Moscow's military takeover of Ukraine. The legislation would also target Russians complicit in corruption.
A possible path for de-escalating the dispute emerged Tuesday, when Crimea's parliament said that if the public votes to become part of Russia, the peninsula will declare itself independent and propose becoming a Russian state. That could give Moscow the option of saying there is no need for Crimea to become part of Russia while keeping it firmly within its sphere of influence.
The U.S. is also calling on Russia to recognize Ukraine's new government, which Moscow has so far said is illegitimate.
Yatsenyuk will be greeted at the White House Wednesday by all of the grandeur of a head of state visit, including an Oval Office meeting with Obama. The two leaders were expected to make brief comments to the media following their discussions.
Vice President Joe Biden, who has served as a primary administration contact with Ukraine's old and new governments, was cutting short a trip to Latin America to attend the meeting. Secretary of State John Kerry, who met with Yatsenyuk in Kiev last week, is expected to have a separate meeting with the prime minister.
Obama and other administration officials are expected to reinforce their commitment to boost Ukraine's fragile new government. The U.S. has promised Ukraine $1 billion in loan guarantees, as well as technical support as it moves toward elections.
Obama has urged Congress to quickly approve the loan guarantee, which is supposed to supplement additional assistance from the International Monetary Fund. The loan guarantee is included in the bill the Senate will consider Wednesday.
A major sticking point had been a provision in the bill to enhance the lending capacity of the IMF. The Obama administration has pushed hard for acceptance of the IMF changes as part of the legislation authorizing the assistance.
The IMF's 2010 revisions expand the power of emerging countries within the global lending body and make some of its funds more readily available. The United States is the only country on the IMF board that hasn't accepted the changes yet.
Sen. Lindsey Graham, R-S.C., said Tuesday he supported the IMF changes and viewed them as a "national security" concern. But several House Republicans have voiced opposition.
The House last week voted overwhelmingly in favor of the loans to Ukraine. The legislation didn't include Russia sanctions or any language on the IMF.
The European Union has pledged $15 billion in assistance to Ukraine, though even that falls well short of the $35 billion in international rescue loans Kiev says it needs over the next two years.
NATO sends 2 surveillance planes to Ukraine border
NATO deployed two surveillance aircraft Wednesday to monitor Ukraine's air space and Black Sea ship movements as Russia consolidated its military buildup in Crimea.
NATO headquarters spokesman Lt. Col. Jay Janzen said one aircraft based in England would observe Russian air and sea movements from Polish air space, while the other based in Germany would fly over Romania. Both Poland and Romania are NATO members and border Ukraine, and Romania's Black Sea coast is only about 220 kilometers (140 miles) from the Crimean peninsula.
Janzen said the planes — both Boeing E-3 Sentry aircraft that sport a rotating radar dome above the fuselage — would be able to monitor military movements covering an area of 300,000 square kilometers (115,000 square miles) and willl not leave NATO air space.
"Regardless, we can observe, we can look, a very long way," he said.
The Sentry is also known as AWACS, short for "airborne warning and control system," and is the main battlefield command and surveillance aircraft for NATO air forces.
The 28-nation NATO alliance decided Monday to use AWACS to monitor Russia's military buildup, and the first Sentry sortie over Romania happened Tuesday, Janzen said.
The U.S. Air Force already has deployed extra combat fighters to NATO bases in Eastern Europe, including six F-15s last week in Lithuania and a dozen F-16s this week in Poland.
Meanwhile, a U.S. Navy destroyer joined Bulgarian and Romanian naval forces in the Black Sea for exercises a few hundred miles off the Crimean peninsula.
The drills on Wednesday include the guided-missile destroyer USS Truxton, the Bulgarian naval frigate Drazki and three Romanian vessels.
Bulgaria's Defense Ministry said in a statement that the drills were planned in 2013 and were in no way related to the recent events in the Ukraine.
— Associated Press reporters Julie Pace, Frank Augstein and Kirsten Grieshaber
Associated Press writer Bradley Klapper contributed to this report.