TBILISI, Georgia—Vice President Dick Cheney assured Georgian leaders Thursday that the U.S. is “fully committed” to Georgia’s pursuit of NATO membership, an assurance likely to further anger a Kremlin bent on keeping the Western military alliance out of former Soviet territory.

Meeting with Georgian President Mikhail Saakashvili in Tbilisi, Georgia’s capital, Cheney used some of the harshest rhetoric yet from Washington against Russia, condemning its invasion and occupation of U.S.-allied Georgia as an “illegitimate, unilateral attempt” to forcibly change its tiny neighbor’s borders.

“Russia’s actions have cast grave doubts on Russia’s intentions and on its reliability as an international partner,” Cheney said.

Cheney’s visit to Tbilisi was the second leg of a tour through U.S.-allied nations that have angered the Kremlin by pursuing integration with the West. On Wednesday, the vice president visited Azerbaijan, an oil-rich former Soviet republic and a vital cog in U.S. attempts to establish an energy corridor that bypasses Russia.

After his visit in Georgia, Cheney was scheduled to fly to Ukraine to meet with President Viktor Yushchenko, who like Saakashvili has been trying to steer his nation toward eventual membership in NATO and economic integration with Europe.

The Kremlin regards NATO’s dialogue with Georgia and Ukraine about membership as a direct threat to Russian national security. Russia has threatened to aim nuclear missiles at Ukraine if that country ever joins NATO, and many experts believe Russia’s underlying goal in invading Georgia was to undermine the Saakashvili government and nullify the country’s chances of NATO membership.

The conflict began Aug. 7, when Georgian troops responded to South Ossetian shelling of ethnic Georgian villages by launching an all-out assault on South Ossetian forces.

Russian troops quickly routed Georgian forces from the breakaway province but then pushed columns of tanks and armored personnel carriers deep into Georgian territory. Large numbers of Russian troops have since withdrawn, but some remain stationed on Georgian land outside of South Ossetia and Abkhazia, another separatist enclave.

While the ongoing conflict, coupled with Russia’s recognition of the independence of South Ossetia and Abkhazia, have destabilized the small Caucasus nation, Cheney stressed that Washington’s commitment to Georgia’s eventual membership in NATO remains strong.

“Georgia will be in our alliance,” Cheney said.

Earlier this week, the Bush administration announced a $1 billion aid package that would help Georgia rebuild its economy and war-damaged infrastructure. Georgian officials have estimated the war’s toll on the country at $1 billion.

The U.S. military has already delivered $30 million in humanitarian aid to Georgia, including food, tents and medical supplies. The new aid package would deliver more humanitarian aid but also would assist in rebuilding roads, bridges and other infrastructure damaged in Russian bombing raids, as well as provide support aimed at revitalizing the country’s economy.

Roughly $430 million of the aid package would have to be approved by Bush’s successor in the White House.