New Delhi, July 7 -- U.S. President Donald Trump and his NATO counterparts are gathering in Turkey on Tuesday for a two-day summit that comes at a turning point in the organization's history as the United States steps back from its traditional security role in Europe.

Ahead of the meeting in Ankara, Trump has insisted on "loyalty" after some NATO countries balked at allowing U.S. forces to use their bases for attacks on Iran. He listed big European members Britain, France, Germany, Italy and Spain for criticism.

A NATO summit is a highly symbolic moment when the 32 member countries of the world's biggest military alliance underline their unshakeable commitment to one another's security. This year, though, the trans-Atlantic bond has rar...