Boris Johnson says intelligence suggests Russia is planning a 'lightning war' on Kyiv

The withdrawal of some British and US diplomats in Kyiv sends a message to Russians that they don't regard them as trustworthy, reports ITV News Senior International Correspondent John Irvine

Boris Johnson has said intelligence suggests Russia is planning a lightning raid on Kyiv, as he warned Vladimir Putin that invading Ukraine would be a “painful, violent and bloody business”.

The prime minister said that an invasion of Ukraine would be a “disastrous step”, which could see Russia bogged down in a protracted conflict with casualties on both sides.

His stark assessment came as some British staff and dependants started to withdraw from the embassy in Ukraine, after intense diplomatic negotiations failed to ease tensions.

Officials said that around half of the staff working in Kyiv will return to the UK.

Boris Johnson warned that intelligence suggested Russia was planning a lightning raid on Kyiv

In an interview on Monday, Mr Johnson said he did not believe war was inevitable, but said defensive weaponry is being supplied to Ukraine to bolster defences against the tens of thousands of Russian troops massed around the border.

“The intelligence is very clear that there are 60 Russian battle groups on the borders of Ukraine, the plan for a lightning war that could take out Kyiv is one that everybody can see," he said.

“We need to make it very clear to the Kremlin, to Russia, that that would be a disastrous step.”

“I think it’s very important that people in Russia understand that this could be a new Chechnya," Mr Johnson added.

'Invading Ukraine, from a Russian perspective, is going to be a painful, violent and bloody business' Mr Johnson said

Later on Monday, Mr Johnson and world leaders including US president Joe Biden agreed to take swift action ”including an unprecedented package of sanctions” in the event of a Russian incursion in Ukraine.

A Downing Street spokeswoman said: “The leaders agreed on the importance of international unity in the face of growing Russian hostility. The prime minister underlined the real human cost of any Russian aggression and the need to take all steps within our power to prevent that outcome.

“The leaders stressed that diplomatic discussions with Russia remain the first priority, and welcomed talks that have already taken place between Russia and Nato allies.

“They also agreed that the international community should not tolerate any action which undermines Ukrainian sovereignty. The prime minister outlined the steps the UK has taken to increase Ukraine’s defensive capacity. He emphasised the need to support Ukraine’s defences against the full spectrum of malign Russian activity.

“The leaders 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.”

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It comes as the Foreign Office pulled some embassy staff out of Ukraine.

The move is a precautionary one, with no specific event believed to have occurred in the last day that led to the decision.

But it comes as the deteriorating security situation has seen Nato reinforce its eastern borders with land, sea and air forces.

John Irvine in Kyiv explains the situation in Ukraine as the country 'remain's Russia's hostage' over its demands for NATO

Members of the Nato alliance, including Denmark, Spain, Bulgaria and the Netherlands, are sending additional ships and fighter jets to Eastern Europe to boost defences in the region.

The Foreign Office's move came after the State Department ordered the families of all American personnel at the US Embassy in Ukraine to leave the country.

The department told the dependents of staffers at the US Embassy in Kyiv that they must leave the country, and said that non-essential embassy staff could leave Ukraine at government expense.

'The main mood is pessimism': Swedish Foreign Minister Ann Linde, who had been taking part in the talks, tells Europe Editor James Mates there is more pessimism than optimism with regards to preventing war

The State Department is also advising US citizens to avoid travel to Russia.

The Ukrainian-Russian tensions were not eased during talks on Friday between Secretary of State Antony Blinken and Russian Foreign Minister Sergey Lavrov in Geneva.

State Department officials stressed the Kyiv embassy will remain open and that the announcement does not constitute an evacuation.

Russian soldiers take part in drills at the Kadamovskiy firing range in the Rostov region in southern Russia. Credit: AP

The UK believes there is a significant risk that Russian president Vladimir Putin will launch a full-scale invasion of Ukraine. Foreign Secretary Liz Truss has accused the president of plotting to install a pro-Moscow leader as head of the Ukrainian government.

Justice Secretary Dominic Raab warned on Sunday there was a “very significant risk” of a Russian invasion of its neighbour. “The world needs to keep its eye on this and be very clear with President Putin that it would not do this cost-free, that there would be a price."

Russia's military muscle-flexing reflects a bold attempt by the Kremlin to halt decades of NATO expansion after the end of the Cold War.

In talks with the United States, Russia demands legally binding guarantees that the alliance will not embrace Ukraine and other former Soviet nations.