Russia must withdraw its military forces from Georgia "now," the White House demanded on Thursday, saying Moscow was in violation of a commitment to do so made earlier this month.
Russia has shown no signs of a full-scale withdrawal of forces from Georgia and has reportedly informed NATO it wants to cease military ties, US officials said.
"For all practical purposes, military-to-military cooperation had really already been suspended with the Russians," White House spokesman Gordon Johndroe said.
"NATO canceled some exercises. And I can't imagine a circumstance right now that we would engage in military cooperation with the Russians until the situation in Georgia is resolved," he said in Texas, where President George Bush is at his ranch.
Bush and Georgia President Mikheil Saakashvili spoke by telephone on Thursday and Bush told him the United States was seeking Russia's compliance with the agreement to withdraw and for "an end to their siege of Georgia," Johndroe said.
Under a French-brokered cease-fire agreement, Moscow had been expected to pull troops out of Georgia, but Pentagon spokesman Bryan Whitman said "there has not been much evidence of any significant Russian withdrawals."
"Russia is in violation of the commitments that they have made," Johndroe said.
The crisis erupted on August 7-8 when Georgia, which has a border with Russia, tried to retake control of South Ossetia, a pro-Moscow region which broke with Tbilisi in 1992.
Russian forces struck back and crossed into the Georgian heartland, overwhelming the army in fierce fighting.
Johndroe said reports from Georgia suggested that if there was any withdrawal taking place, "it's very limited," and there were also reports suggesting that either there were additional Russian troops or that they might be "digging in" to stay.
"The withdrawal needs to take place, and needs to take place now," he said.
State Department spokesman Robert Wood said "a lot of Russian forces are moving around but not moving out" of Georgia.
The United States sees Russia as an important partner on issues like Iran and North Korea, but wants Moscow to resolve the situation with Georgia.
"We're not slamming the door on Russia," Wood said. "However, Russia needs to make a choice about whether it wants to be a part of international institutions and we certainly hope that Russia will make that strategic choice."