The United States and some European countries have shut their embassies in Kiev due to "specific information of a potential significant air attack" amid jitters in the capital over possible Russian retaliation a day after a big Ukrainian strike.
"Out of an abundance of caution, the embassy will be closed, and embassy employees are being instructed to shelter in place," the US Department of State Consular Affairs said in a statement on the embassy's website on Wednesday.
"The US Embassy recommends US citizens be prepared to immediately shelter in the event an air alert is announced."
The Italian, Greek and Spanish embassies said they had also closed their doors after the unusual US warning on Wednesday, while the French embassy remained open but urged its citizens to be cautious.
Germany's embassy in Kiev, on the other hand, remains open in a limited capacity and can still be contacted by German nationals who are in the country, according to a German foreign ministry official.
"We are in constant contact with our colleagues on the ground so that we can take appropriate measures if the situation changes," added the official.
Air raid sirens briefly sounded in Kiev in the afternoon, as the air force told people to seek shelter because of a missile threat. Senior officials told Ukrainians not to ignore the alert.
Ukraine on Tuesday used US ATACMS missiles to attack an arms depot inside Russia, making use of newly granted permission from the outgoing administration of US President Joe Biden on the 1,000th day of the war.
A second ATACMS strike
Russia has been signalling to the United States and its allies for weeks that if they give permission to Ukraine to strike deep into Russian territory with Western-supplied missiles then Moscow will consider it a major escalation.
The embassy in Kiev also urged US citizens in Ukraine to have reserves of water, food and other essentials such as required medications for the event of a "possible temporary loss of electricity and water" caused by Russian strikes.
"Persistent Russian attacks targeting civilian infrastructure throughout Ukraine may result in power outages, loss of heating, and disruption of municipal services," it said.
The Kremlin said it had no comment.
Russian foreign intelligence chief Sergei Naryshkin said in an interview published on Wednesday that Moscow would retaliate against NATO countries that facilitate long-range Ukrainian missile strikes against Russian territory.
Ukraine's military intelligence agency said on Wednesday that a Russian military command post had been "successfully struck" in the town of Gubkin in Russia's Belgorod region, around 168 km (105 miles) from the border with Ukraine.
The Ukrainian statement raised the possibility of a second ATACMS strike, though it did not specify who carried out the attack, when it took place or the type of weapon used. Ukraine has also used drones for deep strikes against targets in Russia.
The war is at a volatile juncture, with a fifth of Ukrainian territory in Russian hands, North Korean troops deployed in Russia's Kursk region and doubts over the future of Western aid as US President-elect Donald Trump returns to the White House.
On Sunday, Russia staged a massive missile and drone strike on Ukraine's national power grid that killed seven people and renewed fears over the durability of the hobbled energy network.
