Hungarian fighter jets were scrambled to intercept an Israeli passenger jet that failed to contact local air traffic control on Thursday.

The Arkia flight, which flew from Tel Aviv to Prague, triggered NATO’s “highest level of alert” after crossing into Hungarian airspace. Two Gripen fighter jets were scrambled to make contact with the Israeli Airbus A321.

Shortly after takeoff, the Gripens established visual contact with the pilots of the passenger aircraft, who subsequently established radio contact with Hungarian ground control.

After contact was made, the flight continued to its destination without incident, During the incident, the Hungarian Defense Forces’ airspace control standby service and the NATO-integrated air defense system operated effectively.

Arkia said “the incident is under internal investigation,” in a statement to Hebrew media outlets.

“The flight crew acted in accordance with the approved flight plan and the pre-determined flight routes,” the low-cost Israeli airline added, saying: “We emphasize that at no point during the flight was there any danger to the plane, passengers, or crew.”