Nato and US urge Russia to back off on Ukraine

Earlier the same day, his secretary of state, Antony Blinken also came to Brussels to speak with Ukraine's foreign minister Dmytro Kuleba and Nato allies' ambassadors.

Blinken voiced "unwavering support for Ukraine's sovereignty and territorial integrity".

US defence secretary Lloyd Austin, who visited Berlin on Tuesday, said the US was posting an extra 500 soldiers to Germany, in a broader show of solidarity with Europe.

And America sent two destroyers to the Black Sea.

For his part, Nato secretary-general Jens Stoltenberg noted the alliance had observed "the largest massing of Russian troops since the illegal annexation of Crimea [by Russia] in 2014".

Depicting Russia's actions as an attempt to prevent Ukraine from Nato integration, he added: "It is for the 30 Nato allies to decide when Ukraine is ready for Nato membership and no one else has any right to try to meddle or to interfere in that process".

Meanwhile, Russia, also on Tuesday, sent mixed messages on what might happen next.

Its defence minister, Sergei Shoigu, called the troop build-up a "preparedness check" that would be wound down in two weeks' time.

But its deputy foreign minister, Sergei Ryabkov, said the US destroyers would be at risk if they came any closer.

"The United States is our adversary ... it will be better for them [the warships] to stay far away from Crimea and our Black Sea coast. It will be for their own good," he said.

The US was "turning Ukraine into a powder keg," Ryabkov added, referring to Western military assistance to Ukraine.

But speaking for Kiev, Kuleba called for Western sanctions on Russia and more military hardware in order to prevent a Russian invasion.

"The price of prevention will still be lower than the price of stopping the war and mitigating its consequences," he told press in Brussels.

"The Russian build-up is taking place not only along the border of Ukraine, but along the border of the democratic world," he added.

"For thousands of kilometres, to the north and to the east of our border with Russia, there is no democracy. So this is a struggle taking place between democracies and authoritarianism," Kuleba said.

There was no talk of Nato fighting Russia in the event of an attack on Ukraine, or of quickly granting Ukraine a membership action plan, however.

The EU has already blacklisted dozens of Russian officials over the Ukraine war and restricted business with Russian banks and energy firms.

But new sanctions options could include locking out Russia from the Swift international bank-transfer system, Manfred Weber, a senior German MEP, said.

The EU could not fully blacklist Gazprom, Russia's state gas firm, "given Europe's dependence on Gazprom-supplied natural gas", Dan Fried, a former senior US diplomat, noted in an op-ed for the Atlantic Council, a Nato-linked think-tank in the US.

Sanctions targets

But the West could stop Gazprom and Russian oil firm Rosneft from raising capital on international markets as well as blacklisting Russia's top lenders, VTB and Gazprombank.

"Blocking some of these banks ... would be appropriate for a scenario where Russian tanks are streaming across Ukraine's border," he said.

He also named Russian oil firm Novatek, steelmaker Evraz, diamond company Alrosa, shipping firm Sovcomflot, and insurance provider Sogaz as potential targets.

Washington previously annoyed Berlin by threatening to sanction European firms taking part in Russia's Nord Stream 2 gas pipeline to Germany, which the US sees as a strategic threat.

But a Russian invasion of Ukraine should also put an end to that project, Fried said.

"A new Kremlin attack on Ukraine might finally get the German government to change course on the pipeline," he said.