Two US F-18 fighters made a rare landing at an Air Force base in Taiwan Wednesday after one of the planes encountered mechanical problems.

The US is going to send personnel to fix the planes and have an American Institute in Taiwan (AIT) official explain the situation. The AIT is the de-facto embassy in Taiwan in the absence of official diplomatic ties between Taiwan and the US.

The two F-18 fighters landed in Tainan at 1:19 pm on Wednesday. They made the emergency landing after requesting permission from Taiwanese authorities.

AIT spokesman Mark Zimmer said the two planes were on a routine flight when one had a mechanical glitch and needed to make an emergency landing. Zimmer also expressed thanks to Taiwan for allowing the landing and allowing mechanical personnel to come fix the plane.

The landing was unusual because the United States does not have formal diplomatic relations with Taiwan, and its military aircraft do not use air bases in Taiwan.