Britain advised against all but essential travel to Israel and the Palestinian territories, and warned of heightened risk of regional tension that could lead to travel disruption and unanticipated impacts, the Foreign, Commonwealth & Development Office reported late on January 14.

The FCDO continues to advise against all travel to parts of Israel and Palestine. "Escalation could lead to travel disruption and other unanticipated impacts," the advisory stated.

"FCDO now advises against all but essential travel to Israel and continues to advise against all travel to parts of Israel and Palestine. There is a heightened risk of regional tension," it announced without citing tensions with Iran.   

The warning came as Britain temporarily withdrew UK staff from its embassy in Iran on January 14, with the mission now operating remotely due to the security situation, IntelliNews reported.

Iran closed the Tehran Flight Information Region to most flights on January 14, with the restriction taking effect from 22:15 UTC through 00:30 UTC on January 15, according to a Notice to Airmen.

Earlier, Germany's aviation authority advised German airlines on January 14 to avoid Iranian airspace through February 10 due to "potential risk to aviation from escalating conflict and anti-aviation weaponry."

Spain's Foreign Ministry issued a complete travel advisory against Iran on January 14, urging Spanish citizens to leave using available means.

Ahead of the airspace announcement, the US Central Command and regional partners opened a new air and missile defence coordination cell at Al Udeid Air Base in Qatar on January 12, designed to enhance coordination and integration for air and missile defence efforts amongst regional partners.

Iranian state media acknowledged "a lot of martyrs" without specifics, while opposition outlet Iran International claims up to 12,000 killed.