ANKARA and WASHINGTON—Air Force One and other leaders’ planes touched down in the Turkish capital today as heads of state and government gathered for this year’s NATO Summit. Yet even with all the aircraft safely on the ground, there could still be turbulence ahead.

In the run-up to the summit, US President Donald Trump cast aspersions on the allies and said that he would have skipped the gathering altogether were it not for his fondness for the host country’s controversial leader, Turkish President Recep Tayyip Erdoğan.

Fortunately, there are several steps NATO leaders can take at the summit to get the Alliance back on the right track.

“Get out alive”

There was reason to believe that this year’s NATO Summit would be smooth sailing. Last year’s summit in The Hague saw all NATO allies make a historic pledge to spend 5 percent of their gross domestic product (GDP) on defense, and many allies are following through.