MOSCOW/KYIV/DONETSK: Russia’s Vladimir Putin has decided to invade Ukraine within days, US President Joe Biden said on Friday after separatists backed by Moscow told civilians to leave breakaway regions on buses, a move the West fears is part of a pretext for an attack.

In one of the worst post-Cold War crises, Russia wants to stop Kyiv joining NATO and accuses the West of hysteria, saying it has no plans to invade, while the US and allies are adamant the military build-up continues.

Warning sirens blared in the breakaway regions of Donetsk and Luhansk on Friday after rebel leaders there announced the evacuation of hundreds of thousands of people to Russia.

“We have reason to believe the Russian forces are planning to and intend to attack Ukraine in the coming week, in the coming days,” Biden told reporters at the White House, adding that Kyiv would be a target.

“As of this moment, I am convinced that he has made the decision.”

Late on Friday, Ukraine’s military intelligence said Russian special forces had planted explosives at social infrastructure facilities in Donetsk, and it urged residents to stay at home. The Russian Federal Security Service did not immediately reply to a request for comment.

Citing correspondents on the ground, Russian news agencies later reported that two explosions hit Luhansk, one of the main cities in Ukraine’s breakaway People’s Republic of Luhansk, and a section of a gas pipeline in the area caught fire.

Earlier, without providing evidence, Denis Pushilin, the separatist leader in Donetsk, accused Ukraine of preparing to attack the two regions soon — an accusation Kyiv said was false.

Asked about the evacuation, White House press secretary Jen Psaki said it was a “good example” of what Washington fears.

“We have … long predicted for all of you that the Russians would take part in pretexts or steps that would lay a predicate for either war or to create confusion or spread misinformation on the ground,” she told reporters.

Hours after the evacuation announcement, a jeep exploded outside a rebel government building in the city of Donetsk.

Reuters journalists saw the vehicle surrounded by shrapnel, a wheel thrown away by the blast. Russian media said it belonged to a separatist official.

Many families in the mostly Russian-speaking area have already been granted citizenship by Moscow and within hours, some were boarding buses at an evacuation point in Donetsk, where authorities said 700,000 people would leave.