Nearly 100,000 Russian troops are gathered within reach of the border with Ukraine in preparation for what Washington and Kyiv say could be a new invasion, eight years after Russia seized the Crimea peninsula from the former Soviet republic.
Russia denies invasion plans and said it is responding to what it calls aggressive behavior from the NATO military alliance and Ukraine, which has tilted toward the West and aspires to join NATO.
Last month, Russia presented sweeping demands including a ban on further NATO expansion and an end to the alliance's activity in central and eastern European countries that joined it after 1997.
Conflicts around the world
Russia has also forcefully intervened in Belarus, where strongman Alexander Lukashenko has cracked down on mass protests triggered by wide accounts of rigging in the 2020 elections, and more recently in Kazakhstan where Russian troops were invited to suppress demonstrations.
In Africa, the United States and the European Union have stepped up pressure against the Wagner group, a private security firm with alleged links to people close to President Vladimir Putin.
The group has been accused of abuses in the Central African Republic and Libya and has reportedly discussed a major contract with Mali.
Western powers have long been at loggerheads with Russia over its crucial support to Syrian President Bashar al-Assad, although on another hotspot, Iran, President Joe Biden's administration has largely welcomed cooperation with Moscow.
Biden's victory reopened diplomacy on arms control between the world's two largest nuclear powers.
The two nations have since reached a five-year extension of the New START nuclear reduction treaty.
Secretary of State Antony Blinken said the United States was ready to discuss new measures to reduce risks in Europe but warned Russia must first withdraw troops from the Ukrainian border.
The Biden administration has vowed to champion democracy against the models of China and Russia and has repeatedly criticised Moscow's rights record.
Courts last month shut down Russia's most prominent rights group, Memorial, a step that would have been a surprise even a few years ago.
The United States has imposed sanctions over the treatment of Putin's most high-profile critic, Alexei Navalny, who was nearly killed in a poisoning in 2020 and then imprisoned on old charges of embezzlement.
The United States has warned its embassy in Moscow could stop functioning this year due to a new ban on hiring local staff.
Washington says Moscow has not been reciprocal in the number of US diplomats permitted in Russia, with former local staff counting against the US allotment.
Among other bilateral issues, the United States has warned Putin to crack down on hackers believed to operate in Russia and has longstanding concerns about Russian disinformation campaigns, most notably during the 2016 election.
The United States has also sought the release of two citizens jailed in Russia, former Marine Paul Whelan and Trevor Reed, who was charged with assaulting police officers while drunk.