Nato member states declared their unity over Ukraine amid worsening tensions with Russia. The military alliance on Monday said it was sending additional fighter jets and ships to eastern Europe, as the Pentagon announced it was putting up to 8,500 US troops on standby
Late on Monday, leaders of the US, Italy, Poland, France, Germany, the European Council, the European Commission and Nato met online to discuss the crisis.
President Joe Biden said the US is in "total unanimity with all the European leaders" and called the meeting "very, very, very good".
British Prime Minister Boris Johnson's office said the "leaders agreed on the importance of international unity in the face of growing Russian hostility".
“The leaders stressed that diplomatic discussions with Russia remain the first priority," a Downing Street statement read.
But they also agreed that "should a further Russian incursion into Ukraine happen, allies must enact swift retributive responses, including an unprecedented package of sanctions. They resolved to continue co-ordinating closely on any such response”.
Amid the heightened security threat, some of those working in the UK's mission to Kiev will return to Britain. And on Sunday, the US State Department announced it was ordering diplomats' family members to leave Ukraine. Its embassy in Kiev said “military action by Russia could come at any time".
The Australian government has "directed the departure" of dependants of its embassy staff from Kiev and urged its citizens to leave Ukraine, warning that "security conditions can change at short notice".
The European Commission also proposed a €1.2 billion ($1.36bn) aid package for Ukraine to help Kiev mitigate the economic effects caused by the build-up of 127,000 Russian troops on the Ukrainian border and fears that an invasion is imminent. Moscow rejects the invasion claims.
“Nato will continue to take all necessary measures to protect and defend all allies, including by reinforcing the eastern part of the alliance,” said Secretary General Jens Stoltenberg as he welcomed additional military support from Denmark, Spain and the Netherlands.
“We will always respond to any deterioration of our security environment, including through strengthening our collective defence,” he said.
The Kremlin accused Nato of increasing tensions through “information hysteria” and “concrete actions".
Meanwhile, the US Department of Defence said it was putting up to 8,500 US-based troops on "heightened alert" to join a Nato response force that could be called up in the crisis at the Ukrainian border.
Pentagon spokesman John Kirby emphasised that no final decision has been made on whether to use the US forces. The standby status means troops will be ready to deploy by the end of the week, if called upon.
This "will ensure that the United States and our commitment to the NRF (Nato Response Force) is consistent with their readiness for rapid deployment ... if activated," Mr Kirby said.
Russia has already invaded Ukraine once, annexing the Crimean Peninsula in 2014, and supported pro-Russian Ukrainian separatists fighting the Kiev government in the Donbass region.
High-level talks between Russia and western capitals have failed to make headway or ease tensions. Moscow has issued a series of controversial demands, including that Nato promises it will never allow Ukraine to join the military alliance. Nato rejected that demand out of hand.
European Commission chief Ursula von der Leyen said the financial aid – comprising emergency loans and grants – was intended to “help Ukraine now to address its rapid escalation in financing needs due to the conflict".
While Ukraine is not a member of Nato or the EU, both have offered the country their support.
An EU statement condemned Moscow’s “continued aggressive actions and threats against Ukraine and calls on Russia to de-escalate”.
“Notions of 'spheres of influence' have no place in the 21st century,” it said.
The EU said it was committed “to the core principles on which European security is built”.
“This includes notably the sovereign equality and territorial integrity of states; the inviolability of frontiers; refraining from the threat or use of force; and the freedom of states to choose or change their own security arrangements.
“These principles are neither negotiable nor subject to revision or reinterpretation. Their violation by Russia is an obstacle to a common and indivisible security space in Europe and threatens peace and stability on our continent.”
Denmark's foreign minister said the EU would be ready to target Russia with heavy sanctions if it attacked Ukraine, but did not say what sectors would be targeted.
The EU and the US imposed economic sanctions on Moscow, hitting its energy, banking and defence sectors, after Russia annexed the Crimea in 2014.
“There's no doubt we are ready to react with comprehensive, never-seen-before sanctions if Russia were to invade Ukraine again,” Jeppe Kofod said on arrival at the EU talks.
Before those talks, Ireland’s foreign minister said Russia's plan to hold naval exercises off the Irish cost were “not welcome” given the current tensions. The drills, scheduled to begin in February, will occur in international waters, but within Irish controlled airspace and the country’s exclusive economic zone.
In compliance with legal requirements, Russia informed Ireland’s aviation authorities of the planned manoeuvre in advance.
“This is not a time to increase military activity and tension in the context of what is happening with and in Ukraine at the moment,” Irish Foreign Minister Simon Coveney said.
“It’s important that I brief my colleagues on those intentions.
“Russia, under international law, can take military exercises in international waters, but the fact they are choosing to do it on the west borders of the EU, off the Irish coast, is something that is in our view not welcome and not wanted right now, particularly in the coming weeks.”