ANKARA, Turkey (AP) — Turkey's defense ministry says Russia has begun delivering the second battery of its S-400 missile defense system that has strained ties between Ankara and Washington.

Turkey took delivery of the first battery of the Russian-made system last month, despite strong objections from its NATO ally, the United States.

Washington says the Russian system is incompatible with NATO and poses a threat to the U.S.-led F-35 fighter jet program. It suspended Turkey's participation in the F-35 program and has threatened sanctions against Ankara.

The Turkish defense ministry said in a statement posted on Twitter that the shipment resumed Tuesday as Turkish media reported that a Russian cargo plane landed at an air base near Ankara.