WASHINGTON (Reuters) — The U.S. Federal Aviation Administration is allowing U.S. airlines to resume operations over large areas of the Persian Gulf, saying that a lower military posture by Iran has reduced the threat of miscalculation or misidentification of civilian flights.

A notice issued on Friday by the FAA rescinded restrictions imposed on U.S. air carriers in early January that prohibited flights over large swaths of the Persian Gulf and the Gulf of Oman as tensions rose between Iran and the United States. The notice applied to the airspaces of Kuwait, Saudi Arabia, Bahrain, the United Arab Emirates and Oman.

The FAA, however, advised U.S. carriers to “exercise caution and avoid operating” near the boundaries of the Tehran flight information region “whenever possible”. “Military posturing and political tensions in the region remain elevated, and there remains some inadvertent risk to U.S. civil aviation operations due to the potential for miscalculation or misidentification”, it said. “The situation in the region remains fluid and could quickly escalate if circumstances change.”

It cited the Jan. 8 accidental downing by Iran of a Ukrainian passenger jet shortly after it departed Tehran’s international airport, killing all 176 people aboard, as showing the inadvertent risk to civilian flights during periods of heightened military tensions.