The United States has sent a group of advanced Raptor stealth fighter jets to Israel as part of a broader military buildup in the Middle East, according to a United States official and a person familiar with the deployment. The move comes just days before a planned round of negotiations with Iran over its nuclear program.

Flight tracking data and images indicate that about a dozen of the aircraft departed from a base in Britain, accompanied by refueling tankers that were later tracked over the Mediterranean Sea. Some of the jets have already arrived in Israel. The deployment is believed to be the first known time this type of aircraft has been sent to Israel during heightened tensions with Iran.

A retired Air Force lieutenant general said the deployment signals preparation for a more aggressive posture toward Iran and the possibility of cooperation with Israel in a strike if diplomatic efforts fail. The aircraft, regarded as among the most advanced stealth fighters in the world, are capable of conducting both air-to-air and air-to-ground missions and have previously taken part in strikes on Iranian nuclear facilities.

The reinforcement adds to a significant United States military presence in the region, which already includes two aircraft carrier strike groups and more than 60 fighter jets stationed in Jordan.