Ukraine’s leaders have urged its people to stay calm in the face of a threatening Russian military build-up close to the country’s borders, as diplomatic efforts to defuse the crisis struggled to keep pace with growing fears of a major war.
Russia has sent more than 100,000 troops and much heavy weaponry towards Ukraine in recent weeks, and threatened to take "military-technical" action if Nato refuses to bar Ukraine and other eastern Europe states from joining the alliance and does not withdraw its forces from the region – demands that Washington calls "non-starters".
The United States sent more arms to Kyiv on Tuesday amid deliveries by several Nato states, while Russian forces continued to roll westward towards the Ukrainian border and into Belarus, Moscow's ally to the north of Ukraine.
"Our armed forces are ready to repel the enemy. Don't worry, sleep well. You don't need to have any kind of emergency bag ready," said Ukrainian defence minister Oleksiy Reznikov.
“I can say absolutely clearly: as of today the Russian armed forces have not formed a battle group that could carry out an invasion of Ukraine.”
After convening his country's security and defence council on Monday night, Ukrainian president Volodymyr Zelenskiy said in a televised address that "everything is under control, there is no reason to panic".
“We know about everything, we are ready for anything, we hope for the best and are doing all we can to achieve it,” he added, while urging Ukrainians to have faith in their soldiers and not to add to their stress “by screaming ‘all is lost!’”
Kyiv officials say Russia could try to undermine the Ukrainian authorities and sow dissent and fear through a combination of disinformation and cyber and physical attacks on infrastructure and other high-profile targets in Ukraine.
Ukraine’s SBU security service said on Tuesday that in “a large-scale operation in Zhytomyr and Kharkiv” its counter-intelligence unit “dismantled an organised criminal group co-ordinated by Russian special services”.
Firearms, ammunition and an explosive device were recovered in the operation, and the group planned “attacks on city infrastructure facilities, including in the commercial sector ... to destabilise the internal situation in the regions”, the SBU added.
The US delivered more weapons and ammunition to Kyiv on Tuesday – its third such delivery in the past week – and British soldiers began instructing Ukrainian troops in the use of anti-tank missiles sent from London last week.
Several Nato states are now bolstering the defences of fellow members in eastern Europe, and the Pentagon is putting up to 8,500 US troops on “heightened alert” for potential deployment in response to developments in and around Ukraine.
"The United States is escalating tensions... We are watching these US actions with great concern," Kremlin spokesman Dmitry Peskov said on Tuesday, as Russia's military began combat-readiness drills in regions near Ukraine involving about 6,000 soldiers and 60 warplanes.
Moscow says it feels threatened by the Nato membership ambitions of Ukraine and Georgia – though their accession is an extremely distant prospect - and the possibility of US missile systems being placed on their territory or in other countries near Russia.
It expects to receive written responses to its long list of security demands from the US and Nato this week, after which more talks may take place following four rounds of fruitless discussions in various formats earlier this month.
French president Emmanuel Macron discussed the crisis with German chancellor Olaf Scholz on Tuesday, and is expected to talk to Mr Zelenskiy and Russian president Vladimir Putin in the coming days.
Senior political advisers from Ukraine, Russia, Germany and France will meet in Paris on Wednesday for talks on the eight-year war in eastern Ukraine between government forces and Moscow-led separatists, which has killed 14,000 people.