When NATO leaders arrive at Recep Tayyip Erdogan¡¯s vast, 1,000-room complex in Ankara next week, the Turkish president is expected to tell them how vital his country is to a military alliance in trouble. It¡¯s a separate event in the city, though, that will demonstrate that importance.

Motorcades en route to Erdogan¡¯s palace will pass military equipment parked outside the Turkish capital¡¯s exhibition center. Inside, stands showing off ammunition and electronic warfare systems will highlight Turkey¡¯s flourishing $10 billion arms export industry.

With a deterioration in transatlantic relations, Europe is finding out just how useful Turkey can be.