The United States closed its embassy in Kyiv on Nov. 20 and warned American citizens in Ukraine to be ready to swiftly seek shelter after receiving “specific information of a potential significant air attack.”

The embassy also urged Americans in Ukraine to follow the directions of Ukrainian officials and first responders in the event of an emergency and to monitor local media.

The Italian and Greek embassies in Kyiv also shut to the public for the day. The British government stated that its embassy in the city remained open.

The warning comes a day after the Russian Ministry of Defense reported that Ukraine used U.S.-made long-range Army Tactical Missile Systems (ATACMS) to strike its territory.

The defense ministry stated that Russian forces shot down five of six missiles fired at a military facility in the Bryansk region in Russia.

Fragments from one of the missiles hit the military facility, causing a fire that was quickly extinguished and caused no casualties or damage, according to the ministry.

Biden, who is set to leave office in two months, has previously opposed allowing U.S. missiles to be used deep inside Russia.

Following the move, the White House stated that it has no plans to adjust its nuclear posture in response to Russia’s actions.

Kremlin spokesman Dmitry Peskov on Nov. 18 accused the Biden administration of “adding fuel to the fire” and “provoking further escalation.”

“President Putin has already explained it very simply. Ukraine does not carry out these strikes. After all, the strikes are carried out by those countries that give permission, because the Ukrainian military does not acquire the targets and provide the maintenance,” Peskov said. “This is done by military specialists from these Western countries, and this fundamentally changes the modality of their involvement in the conflict. This is the danger and the provocative nature of this situation.”

Zelenskyy added that Ukraine “will use all of these.”