U.S. Secretary for Defense Jim Mattis, right, arrives for a meeting at NATO headquarters in Brussels on Thursday, June 29, 2017. NATO defense ministers meet Thursday to discuss, among other issues, the situation in Afghanistan and defense spending. (AP Photo/Virginia Mayo, Pool)
U.S. Secretary for Defense Jim Mattis, left, walks with NATO Secretary General Jens Stoltenberg prior to a meeting at NATO headquarters in Brussels on Thursday, June 29, 2017. NATO defense ministers meet Thursday to discuss, among other issues, the situation in Afghanistan and defense spending. (AP Photo/Virginia Mayo, Pool)
NATO Secretary General Jens Stoltenberg speaks during a media conference at NATO headquarters in Brussels on Wednesday, June 28, 2017. NATO defense ministers meet on Thursday to discuss, among other issues, the situation in Afghanistan. (AP Photo/Virginia Mayo)
NATO Secretary General Jens Stoltenberg speaks during a media conference at NATO headquarters in Brussels on Wednesday, June 28, 2017. NATO defense ministers meet on Thursday to discuss, among other issues, the situation in Afghanistan. (AP Photo/Virginia Mayo)
A Romanian serviceman furls the NATO flag after Britain's Defense Minister Michael Fallon's visit at the Mihail Kogalniceanu air base in Romania, Wednesday, June 14, 2017. Britain's defense minister praised Romanian and British pilots for protecting the Black Sea region from "the persistent threat of Russian aggression," saying that Britain remains committed to NATO and the European security.(AP Photo/Vadim Ghirda)
British Prime Minister Theresa May, left, looks away from U.S. President Donald Trump after he spoke during a ceremony at the NATO summit in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Geert Vanden Wijngaert)
In this May 25, 2017, photo, NATO Secretary General Jens Stoltenberg listens as President Donald Trump speaks during a ceremony to unveil artifacts from the World Trade Center and Berlin Wall for the new NATO headquarters in Brussels. It’s been a muted week for Trump when it comes to tweeting. But AP Fact Checks have spotted some tall tales in his rhetoric during his first foreign trip since taking office. For one, Trump claimed that fellow NATO members “owe massive amounts of money” to the common defense. They don’t.(AP Photo/Evan Vucci)
US President Donald Trump smiles during a tour of the new NATO headquarters during a NATO summit of heads of state and government in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Matt Dunham)
US President Donald Trump arrives to meet NATO Secretary General Jens Stoltenberg during a NATO summit of heads of state and government in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Matt Dunham)
US President Donald Trump, center, speaks with NATO Secretary General Jens Stoltenberg, right, during a NATO summit of heads of state and government in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Matt Dunham)
Turkish President Recep Tayyip Erdogan arrives for the NATO summit in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Geert Vanden Wijngaert)
Turkish President Recep Tayyip Erdogan, left, arrives for the NATO summit in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Geert Vanden Wijngaert)
British Prime Minister Theresa May arrives for the NATO summit in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Geert Vanden Wijngaert)
NATO Secretary General Jens Stoltenberg, right, greets US President Donald Trump during a NATO summit of heads of state and government in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Matt Dunham)
US President Donald Trump, left, speaks with Lithuanian President Dalia Grybauskaite during a tour of the new NATO headquarters during a NATO summit of heads of state and government in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Matt Dunham)
NATO Secretary General Jens Stoltenberg, right, greets US President Donald Trump during a NATO summit of heads of state and government in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Matt Dunham)
NATO Secretary General Jens Stoltenberg, right, greets US President Donald Trump during a NATO summit of heads of state and government in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Matt Dunham)
Turkish President Recep Tayyip Erdogan arrives for the NATO summit in Brussels on Thursday, May 25, 2017. US President Donald Trump and other NATO heads of state and government on Thursday will inaugurate the new headquarters as well as participating in an official working dinner. (AP Photo/Geert Vanden Wijngaert)