Austria's air force scrambled two fighter jets Monday to intercept a French turboprop plane when the aircraft failed to make contact with Austrian authorities after entering the alpine nation's airspace, officials said.
The two F5 jets instructed the unidentified French pilot to establish radio contact, and after doing so he was allowed to continue on his way to Slovakia, air force Lt. Col. Oskar Krasser said.
"The pilot of the civilian aircraft may have forgotten to make contact or simply could not find the proper frequency," Krasser said.
Austrian aviation authorities have tightened surveillance since the Sept. 11, 2001, attacks in the United States, reports the AP.
Photos show many anti-Ukrainian and anti-EU slogans that the farmers use in their demonstration. One of the banners attached to a tractor calls on Russian President Vladimir Putin to bring "Ukraine, Brussels and our rulers” to order