What you need to know:
- The Kremlin said Tuesday it remained open to all diplomatic contact over Ukraine and that Kyiv cutting ties with Moscow would worsen an already tense situation.
- But the Ukrainian leader Volodymyr Zelensky said Russian President Vladimir Putin's actions on Monday demanded a swift and punishing economic response from the West.
From Russia's massing of soldiers along the border in November to Vladimir Putin ordering troops into eastern separatist areas, here is a timeline of months of tensions around Ukraine.
On November 10, 2021, Washington reports unusual Russian troop movements near the Ukrainian border.
On November 28, Ukraine says Russia is massing nearly 92,000 troops for an offensive at the end of January or early February.
Moscow denies this and accuses Kyiv of a military build-up of its own, demanding "legal guarantees" that it will never join NATO.
On December 7, US President Joe Biden threatens Russian counterpart Putin with "strong economic and other measures" if he invades Ukraine.
Ten days later, Moscow puts forward proposals to limit US and NATO influence on former Soviet states.
Build-up in Belarus
On January 17, Russian troops begin arriving in ex-Soviet Belarus for military drills, which Moscow says are aimed at "thwarting external aggression".
Two days later, Washington announces an extra $200 million in security aid to Kyiv.
NATO on standby
On January 24, NATO puts troops on standby and sends ships and fighter jets to bolster Europe's eastern defences.
The next day, Moscow begins military exercises involving some 6,000 troops and at least 60 fighter jets in southern Russia near Ukraine and in Moscow-annexed Crimea.
On January 26, Washington refuses to shut the NATO door on Ukraine and the alliance says many of Moscow's security demands are "unrealistic".
China warns US
The United States says it believes Putin "is going to use military force between now and the middle of February".
The next day, China warns that Russia's security concerns should be "taken seriously".
On January 28, Putin says the West has ignored "Russia's fundamental concerns" on NATO's expansion and has "strike weapons systems near Russia's borders".
Manoeuvres in Belarus
On February 2, the United States sends 3,000 troops to fortify NATO forces in eastern Europe.
Russia and Belarus begin 10 days of military manoeuvres on February 10.
Retreat or reinforcement?
On February 15, Moscow says some of its forces are returning to their bases. But NATO sees no sign of a withdrawal and Washington claims Russia is in fact sending reinforcements.
On February 17, shellfire intensifies all along the frontline of the two Russian-backed enclaves in eastern Ukraine.
A day later, the leaders of the Donetsk and Lugansk separatist regions say they are evacuating residents to Russia.
US Secretary of State Antony Blinken accuses Moscow of "false provocations" to justify further "aggression" against Ukraine.
On February 19, Ukraine says two of its soldiers died in attacks on the frontline with Russian-backed separatists.
Ukrainian President Volodymyr Zelensky proposes a meeting with Putin, as Moscow test-fires nuclear-capable missiles.
Russia is "on the brink" of invading Ukraine, Washington says.
France and Germany call on their nationals to leave Ukraine.
On Monday France says that Putin and Biden have agreed in principle to a summit.
But the White House is notably cautious and the Kremlin says it is too early.
The Russian military says it has killed five "saboteurs" who crossed into Russia from Ukraine. Ukraine denies the claims.
Putin recognises separatist republics
In a televised address, Putin recognises the independence of two separatist regions in eastern Ukraine. The EU vows sanctions.
Putin orders Russian troops into separatist areas in eastern Ukraine on a "peacekeeping" mission.
Condemnation and sanctions
Several hours later during an emergency Security Council session, the UN and most of its members denounce the Russian decisions.
Washington says it will slap new sanctions on Russia.
The EU will also adopt sanctions, the bloc's foreign policy chief Josep Borrell says.
Moscow says Russian Foreign Minister Sergei Lavrov is still ready for talks with Blinken, whom he is scheduled to meet in Geneva on Thursday.