BEIRUT, Lebanon — Turkey sharply escalated its confrontation with Syria on Wednesday, forcing a Syrian passenger plane to land in Ankara on suspicion of carrying military cargo, ordering Turkish civilian airplanes to avoid Syria’s airspace and warning of increasingly forceful responses if Syrian artillery gunners keep lobbing shells across the border.

NTV television in Turkey said two Turkish F-16 warplanes had been sent to intercept a Syrian Air jetliner, an Airbus A320 with 35 passengers en route from Moscow to Damascus, and had forced it to land at Esenboga Airport in Ankara, the capital, because it might have been carrying a weapons shipment to the Syrian government. Inspectors confiscated what NTV described as parts of a missile and allowed the plane to resume its trip after several hours. The Turkish authorities declined to specify what had been found.

“There are items that are beyond the ones that are legitimate and required to be reported in civilian flights,” Turkey’s foreign minister, Ahmet Davutoglu, said in remarks reported by the country’s semiofficial Anatolian News Agency. “There are items that we would rate as troublesome.”