Vladimir Putin has decided to attack Ukraine and will target Kyiv, says Joe Biden

Joe Biden on Friday night said Vladimir Putin has made the decision to invade Ukraine "within days", including a targeted attack on the capital Kyiv.

The US President, speaking with more certainty than in recent weeks, said diplomatic outreach to the Russian president had failed and troops were set to move on Ukraine within the week.

Asked how the US could be certain, Mr Biden said during an evening address at the White House: “We have significant intelligence capability.” Previously US officials had said they did not know if Mr Putin had decided to invade.

Mr Biden, speaking after a phone call with Boris Johnson and Nato allies, warned Moscow against a “catastrophic and needless war of choice” and said the US and its partners “are prepared to defend every inch of Nato territory."

Minutes before he spoke, reports emerged that an international oil pipeline running through the Russian-backed separatist city of Lugansk in eastern Ukraine had been blown up. The pipeline, which was pictured in flames, supplies parts of Europe.

Boris Johnson will on Saturday rally Western leaders to show solidarity “beyond anything we have seen in recent history” to avert bloodshed in Ukraine.

The Prime Minister will fly to the Munich Security Conference to affirm support for heavy sanctions on Russia if it launches an invasion of Ukraine.

It comes after pro-Moscow separatists began to evacuate citizens from the breakaway statelets of Donetsk and Luhansk in eastern Ukraine on Friday, claiming the Kyiv government was preparing an attack.

On Friday night, a gas pipeline in Ukraine’s breakaway region of Luhansk caught fire after a powerful explosion. It was not immediately clear who or what was behind the attack on the pipe, which provides a limited amount of gas to Europe.

The episode fuelled fears that the Kremlin is building a prefabricated pretext for an invasion, with speculation mounting that a false flag attack could be launched on civilians fleeing to Russia.

Mr Putin ordered his emergencies minister to fly to Rostov, the Russian region set to receive the refugees, to organise crisis shelter. Russian media also described a car bomb near a headquarters used by separatists in Donetsk as an act of “terrorism”.

Ukraine’s defence intelligence agency claimed to have intelligence that Russian agents had planted bombs on “social infrastructure” in Donetsk and urged residents of the separatist-held city to stay at home and not use public transport.

In a statement posted on Facebook and Twitter, it said:

Earlier this week, Antony Blinken, the US secretary of state, warned that Moscow could use purported attacks on the Russian-speaking minority as a “manufactured pretext” for an invasion of its neighbour.

The US envoy to the Organisation for Security and Co-operation in Europe reported on Friday that between 169,000 and 190,000 Russian troops are currently stationed close to the Ukrainian border – up from 100,000 at the end of January.

Western officials confirmed that Russia now has sufficient forces in place to “act at scale very quickly” and with “very little or no notice”, adding that the crisis has reached its “most dangerous phase”.

While stressing that it remained “very difficult to read Vladimir Putin’s mind” about what he was planning, the sources acknowledged that the prospects for diplomacy “are not looking great at the moment”.

Mr Putin used a press conference in Moscow to declare that Russia needed to prepare for further sanctions, arguing that the West was always likely to find a reason to impose them on Russia.

On Saturday, he will oversee drills by Russia’s nuclear forces, including ballistic and cruise missile launches, in the latest show of strength. The Kremlin’s spokesman denied the move indicated an escalation in the crisis.

Russia has declined to send a delegation to the annual security summit in Munich, the world’s largest annual gathering of international leaders and foreign policy experts, for the first time in decades.

In a speech there on Saturday, Mr Johnson is set to call on allies to stay united in the face of Russian hostility and “speak with one voice” to warn Mr Putin of the “high price he will pay for any further Russian invasion of Ukraine”. A Moscow-led attack would “devastate” Ukraine, Russia and the rest of Europe, he will stress.

Intense discussions over sanctions took place at the conference on Friday, with Annalena Baerbock, Germany’s foreign minister, warning Washington that any US measures being lined up should not hit Berlin harder than Moscow.

Amid concerns that Germany has been less robust than other Western allies on the need to reduce Europe’s reliance on Russian hydrocarbons, she insisted“all options are on the table” on sanctions, including the Nord Stream 2 pipeline, intended to bring Russian gas to Germany.

Ms Baerbock said Western powers were united in their preparation of “unprecedented sanctions” against Moscow if it invades Ukraine, adding: “We, Germany, are prepared to pay a high economic price for this.”

Attending the panel discussion as an audience member, Vitaly Klitschko, the Kyiv mayor, said Ukraine needed Germany to deliver “defensive weapons”.

Questions were also raised about how the West would determine whether to impose sanctions on Moscow if the Kremlin ordered unconventional attacks on Ukraine but stopped short of a full invasion.

Western officials admitted that the “reality is... it would be more difficult to call exactly when a line had been crossed”.

Stressing that the West still wanted to pursue a diplomatic solution, Kamala Harris, the US vice-president, said: “We understand and we have made clear that we remain open to diplomacy. The onus is on Russia at this point, to demonstrate that it is serious in that regard.”

The British embassy announced on Friday that it was relocating its embassy from Kyiv to Lviv, to which it has already relocated some staff.