U.S. Vice President Dick Cheney is in Kyiv, his latest stop on a tour aimed at showing support for U.S. allies after Russia's conflict with Georgia last month.
Cheney has arrived in Kyiv in the middle of a political crisis.
Just two days ago, President Viktor Yushchenko announced the collapse of the coalition government, after the prime minister sided with the opposition to trim his powers.
Cheney earlier held separate talks with the country's infighting leaders.
First, a meeting with Prime Minister Yulia Tymoshenko. Afterward, spokeswoman Megan Mitchell said Cheney told her Ukraine faced a "challenging time" because of Russia.
Then, talks with Yushchenko. Like his Georgian counterpart, the Western-oriented Yushchenko has pushed strongly for his country's integration into NATO, a prospect that Russia opposes.
After their talks, Cheney said Washington supported Ukraine's bid to join the military alliance, and that a NATO commitment to eventually admit the former Soviet republic "stands today."
"No outside country gets a veto," he said.
Cheney kept up the pressure on Russia over its actions in Georgia, too. He said Georgia had been "subjected to a Russian invasion, and an illegitimate, unilateral attempt by force of arms to dismember its territory."
He added that people should be able to live without fear of "economic blackmail or military invasion or intimidation."
Yushchenko, meanwhile, said Ukraine had "an understanding" with the United States on most issues, including Russian military intervention in Georgia.
But as Cheney held his talks in Kyiv, Russia was responding to his earlier remarks in Tbilisi.
There on September 4, Cheney strongly rebuked Russia for its war with Georgia, highlighted the $1 billion Washington has promised Tbilisi, and reiterated U.S. support for Georgia's efforts to join NATO.
The aid, the comments -- all, said Russian Foreign Ministry spokesman Andrei Nesterenko, encouraged Georgia's "aggressive ambitions."
"Once again, we heard blustering rhetoric about Washington's full support for, I quote, a 'courageous young democracy,'" Nesterenko said.
"Such statements, and particularly new promises of quick NATO membership for Tbilisi, only strengthen Mr. Saakashvili's regime's dangerous sense of impunity and encourage his aggressive ambitions."
Cheney's tour also comes as military tensions mount in the Black Sea.
The flagship of the U.S. Navy's Mediterranean fleet has arrived in the key Georgian port of Poti, where Russian troops have been patrolling since last month's war.
U.S. officials say the "Mount Whitney" is bringing humanitarian aid, but Russia has criticized the move, saying a sophisticated warship is unsuited for an aid mission.
However, asked what Russia's reaction might be, spokesman Nesterenko said, "There is no talk of military action."
Cheney is due to round up his Kyiv trip with a visit to the memorial to Ukraine's 1930s famine, before heading later in the day for Italy.
compiled from agency reports