Biden wants to focus on China. Putin has other plans.

President Joe Biden arrived in the White House 10 months ago with two top foreign policy priorities: He wanted to rebuild the alliances his predecessor had trashed, and he wanted to focus on the U.S. competition with China.

History, and other great powers, don't always cooperate with presidents' grand designs.

The most dangerous international crisis at the moment has come not from Asia, but from a more traditional nemesis, Russia's Vladimir Putin.

Biden has little choice but to deal with Putin's challenge — and his Republican opponents could advance U.S. interests if they stopped denying the president the tools he needs to do so.

Putin's goal, which he has expressed bluntly and often, is to restore Russia's sway over the empire it lost in 1991 when the Soviet Union collapsed. His immediate aim is to reverse the expansion of NATO, the U.S.-led military alliance, to Russia's western borders.

Putin has assets at his command: a surprisingly strong economy with soaring oil revenue, control over much of Europe's natural gas supply, a military skilled in covert warfare and the ruthlessness to act brutally when it suits him.

In recent months, he has warned neighboring countries, including Poland and the three small Baltic republics, all NATO members, that he considers their integration into the alliance an unfriendly act.

In his most threatening action, Putin has moved more than 90,000 troops to the borders of Ukraine, the former Soviet republic that Putin invaded in 2014 to seize the Crimean peninsula.

The danger of a full-scale invasion has thrown the United States and its allies into crisis-prevention mode.

Defense Secretary Lloyd J. Austin III hosted Ukraine's defense minister at the Pentagon earlier this month and delivered Coast Guard cutters to Kiev's navy. British officials said they were preparing 600 troops for deployment to Ukraine. French President Emmanuel Macron said his country would "defend Ukraine's territorial integrity."

But they all stopped conspicuously short of saying they were willing to go to war for Ukraine — because they aren't.

Putin, by contrast, sees Kiev's alignment with the West as a direct threat.

And he has long warned that NATO membership for Ukraine is a "red line." (The North Atlantic Treaty Organization has told Ukraine it can apply for membership, but has carefully held off on beginning the formal process.)

In recent months, Putin has moved his red line closer. Earlier this month he suggested that any NATO presence in Ukraine, including military aid and training, might cross the line.

To Putin, NATO advisers and equipment are gradually transforming Ukraine into a de facto satellite of the Western alliance. He's not entirely wrong.

Russia experts believe he probably doesn't want to invade all of Ukraine — a move that would be costly in military, economic and diplomatic terms — so much as he wants to stop the country's westward drift.

"Putin doesn't want Ukraine to have any interaction whatever with NATO," Fiona Hill, a National Security Council official during the Trump administration, told me last week. "He wants Ukraine to be entirely, irrevocably neutral."

So the United States and its allies are trying to deter Putin from going to war, sending public warnings and private messages about the consequences of an invasion.

What they need most is to reach and make public a consensus on specific sanctions they would apply in the event of Russian military action. But European countries, whose economies are more closely tied to Moscow than ours, are reluctant to commit.

"This is a test of our ability to engage in collective action," Hill said.

A second useful step would be an offer from Biden to talk the problem out; Putin likes being taken seriously as the leader of a superpower.

The president shouldn't accede to Putin's demands that Western countries limit military aid to Kiev, but he can make it clear that the assistance is solely for defensive purposes and that it doesn't mean Ukraine will move any closer to NATO membership.

"We can't put pressure on our counterparts in a crisis if we don't have an ambassador," Hill said; lower-ranking diplomats "don't have the same power."