WASHINGTON (AP) — In a major break with a longtime ally, the Trump administration on Wednesday said Turkey is being kicked out of an American-led fighter aircraft program because it is buying a Russian air defense system that would aid Russian intelligence.

The decision has significant implications for the cohesion of NATO, whose central strategic purpose is to defend against Russian aggression. Now that NATO member Turkey has chosen to buy and deploy the Russian-made S-400 air defense, it will no longer be fully part of the alliance's air defenses, which are at the core of NATO strategy.

The...