The U.S. shuts down its embassy in Kyiv due to possible 'air attack' as tensions with Russia escalate.

• On Wednesday, the U.S. embassy in Kyiv shut down and issued a warning about a possible significant air attack, as tensions with Russia continue to escalate.
• The U.S. Embassy announced that it was shutting down its building "as a precautionary measure" and directed its staff to remain indoors.
• The U.S. Embassy advises U.S. citizens to be ready to take cover immediately if an air alert is issued.

On Wednesday, the U.S. embassy in Kyiv shut down and issued a warning about a possible significant air attack, as tensions with Russia continue to escalate.

The U.S. Embassy announced that it was shutting down its building "as a precautionary measure" and directed its staff to remain indoors.

The U.S. Embassy advises U.S. citizens to be ready to take cover immediately if an air alert is issued.

The latest air alert in Kyiv is happening amid rising tensions between Moscow and Washington, following reports that the White House granted Ukraine permission to use U.S.-made long-range missiles to attack targets on Russian territory.

On Tuesday, Russia's defense ministry announced that it had intercepted five U.S.-made ATACMS missiles and destroyed one other, which had been used by Ukraine to attack its border region of Bryansk. Ukraine has not officially confirmed whether it carried out an attack using long-range American-made missiles.

The Pentagon also declined to comment when asked about the development.

Moscow reacted furiously to the attack, with Foreign Minister Sergei Lavrov labeling it an "escalation" by the West.

Russia has repeatedly cautioned the West against permitting Ukraine to utilize long-range weapons against targets situated on Russian soil. On Tuesday, President Putin approved changes to Russia's nuclear doctrine, modifying the conditions under which Moscow can employ nuclear weapons.

Any aggression against Russia by a non-nuclear state that is supported by a nuclear power will be considered as a joint attack.

The Kremlin may use nuclear weapons if there is a severe threat to its sovereignty and territorial integrity, as well as that of its ally, Belarus. The launch of ballistic missiles against Russia could trigger a nuclear response.