Russia has started evacuating its embassy in Kyiv and Ukraine urged its citizens to leave Russia as the region braced for further confrontation after Vladimir Putin received authorisation to use military force outside his country and the West responded with sanctions.

Hopes for a diplomatic way out of a potentially devastating war appeared all but sunk as the US and key European allies accused Moscow on Tuesday of crossing a red line in rolling over Ukraine’s border into separatist regions — with some calling it an invasion.

Russia began pulling personnel from its diplomatic posts in Ukraine, state news agency Tass reported, a day after the Foreign Ministry announced a plan to evacuate, citing threats.

By Wednesday afternoon, the Russian flag was no longer flying over the embassy in Kyiv, according to an Associated Press photographer. Police surrounded the building.

After weeks of trying to project calm, Ukrainian authorities signalled increasing concern on Wednesday. The Foreign Ministry advised against travel to Russia and recommended anyone there leave immediately, saying Moscow’s “aggression” could lead to a significant reduction in consular services.

The head of Ukraine’s National Security and Defence Council called for a nationwide state of emergency — subject to parliamentary approval.

Oleksiy Danilov said it will be up to regional authorities to determine which measures to apply, but they could include additional protection for public facilities, restrictions on traffic, and more transport and document checks.

It was the latest in a series of signs of escalating tensions, after Kyiv recalled its ambassador to Russia and considered breaking all diplomatic ties with Moscow.

Elsewhere, dozens of nations further squeezed Russian oligarchs and banks out of international markets, Germany halted a lucrative pipeline deal, the US repositioned additional troops to Nato’s eastern flank bordering Russia, and the top US diplomat cancelled a meeting with his Russian counterpart.

The threat of war has shredded Ukraine’s economy and raised the spectre of massive casualties, energy shortages across Europe and global economic chaos.

Even as the conflict took a dangerous turn, leaders warned it could still get worse. Russian President Vladimir Putin has yet to unleash the 150,000 troops massed on three sides of Ukraine, while US President Joe Biden said even tougher sanctions which could cause economic turmoil for Russia would go ahead if there is further aggression.

European Union sanctions against Russia took effect on Wednesday, targeting several companies along with 351 Russian legislators who voted for a motion urging Mr Putin to recognise the rebel regions, and 27 senior government officials, business executives and senior military officers.

German foreign minister Annalena Baerbock called the EU sanctions just “a first step”, and said further measures could follow. Sanctions are key because the West has ruled out taking on Russia militarily.

Ukrainian foreign minister Dmytro Kuleba urged western leaders not to wait.

“We call on partners to impose more sanctions on Russia now,” he wrote on Twitter on Wednesday. “Now the pressure needs to step up to stop Putin. Hit his economy and cronies. Hit more. Hit hard. Hit now.”

The Russian ambassador in the US, Anatoly Antonov, retorted that “sanctions cannot solve a thing”, adding: “It is hard to imagine that there is a person in Washington who expects Russia to revise its foreign policy under a threat of restrictions.”

In Ukraine’s east, where an eight-year conflict between Russia-backed rebels and Ukrainian forces has killed nearly 14,000 people, violence also spiked again. One Ukrainian soldier was killed and six more sustained injuries after shelling by the rebels, Ukrainian military said.

Separatist officials reported several explosions on their territory overnight and three civilian deaths.

Since last Friday, when separatist leaders in the Donetsk and Luhansk regions announced mass evacuations into Russia, more than 96,000 residents of the separatist areas have crossed the Russian border.

After weeks of rising tensions, Mr Putin took a series of steps this week that dramatically raised the stakes. First, he recognized the independence of those separatist regions, then he said that recognition extends even to the large parts of the territories now held by Ukrainian forces, including the major Azov Sea port of Mariupol.

Finally, he asked for and was granted permission to use military force outside the country — effectively formalising a Russian military deployment to the rebel regions.

He suggested there was a way out of the crisis – if Kyiv would recognise Russia’s sovereignty over Crimea, renounce its bid to join Nato, and partially demilitarise – but it was unclear if there was any room for diplomacy since the first two demands had been previously rejected by Ukraine and the West.

Ukrainian government and banking websites were knocked offline on Wednesday with another wave of distributed-denial-of-service attacks.

The targets included the defence, foreign and interior ministries, as well as Privatbank, the country’s largest commercial bank.

Many of the same sites were hit in February 13-14 attacks that the US and UK governments quickly blamed on Russia’s GRU military intelligence agency.

Ukrainian President Volodymyr Zelensky on Wednesday reiterated his call for talks with Mr Putin.

“Many times I suggested to the president of Russia to sit down at the negotiating table and talk. This is a question of dialogue, not a question of ‘condition’,” he said after a meeting with the presidents of Poland and Lithuania.

The Russian leader remained vague when asked whether he had sent any Russian troops into Ukraine and how far they could go, while separatist leader in Donetsk Denis Pushilin said on Wednesday that there were no Russian troops in the region.

His remarks contradict those of Vladislav Brig, a member of the separatist local council in Donetsk, who told reporters on Tuesday that Russian troops had already moved in.