WASHINGTON, Jan 24 - The Pentagon ordered 8,500 troops on higher alert Monday to potentially deploy to Europe as part of a NATO “response force” amid growing concern that Russia could soon make a military move on Ukraine, The Associated Press reported.

President Joe Biden consulted with key European leaders, underscoring U.S. solidarity with allies there, the report said.

Putting the U.S.-based troops on heightened alert for Europe suggested diminishing hope that Russian President Vladimir Putin will back away from what Biden himself has said looks like a threat to invade neighboring Ukraine.

At stake, beyond the future of Ukraine, is the credibility of a NATO alliance that is central to U.S. defense strategy but that Putin views as a Cold War relic and a threat to Russian security. For Biden, the crisis represents a major test of his ability to forge a united allied stance against Putin.

Pentagon press secretary John Kirby said about 8,500 U.S.-based troops are being put on alert for possible deployment — not to Ukraine but to NATO territory in Eastern Europe as part of an alliance force meant to signal a unified commitment to deter any wider Putin aggression.

Russia denies it is planning an invasion. It says Western accusations are merely a cover for NATO’s own planned provocations. Recent days have seen high-stakes diplomacy that has failed to reach any breakthrough, and key players in the drama are making moves that suggest fear of imminent war. Biden has sought to strike a balance between actions meant to deter Putin and those that might provide the Russian leader with an opening to use the huge force he has assembled at Ukraine's border.

Biden held an 80-minute video call with several European leaders on the Russian military buildup and potential responses to an invasion.

“I had a very, very, very good meeting -- total unanimity with all the European leaders," Biden told reporters at the White House. "We’ll talk about it later.”

The White House said the leaders emphasized their desire for a diplomatic solution to the crisis but also discussed efforts to deter further Russian aggression, “including preparations to impose massive consequences and severe economic costs on Russia for such actions as well as to reinforce security on NATO’s eastern flank.”

A day earlier, the State Department had ordered the families of all American personnel at the U.S. Embassy in Kyiv to leave the country, and it said that nonessential embassy staff could leave at U.S. government expense.

Ukraine’s Foreign Ministry spokesman, Oleg Nikolenko, said that U.S. decision was “a premature step” and a sign of “excessive caution.” He said Russia was sowing panic among Ukrainians and foreigners in order to destabilize Ukraine.

Britain said it, too, was withdrawing some diplomats and dependents from its Kyiv Embassy. Prime Minister Boris Johnson said an invasion was not inevitable but “the intelligence is pretty gloomy.” (ap/ez)