The author is Reuters Breakingviews columnist. The opinions expressed are his own.
After the Soviet Union fell, NATO expanded. It also lost its main purpose: taking on that same Soviet Union.
Donald Trump at his caucus night rally in Des Moines, Iowa, February 1, 2016. REUTERS/Jim Bourg
Displaced people from the minority Yazidi sect, fleeing violence from forces loyal to the Islamic State in Sinjar town, near the Syrian border town of Elierbeh of Al-Hasakah Governorate, August 11, 2014. REUTERS/Rodi Said
Donald Trump speaks on the USS Iowa in San Pedro, Los Angeles, California, September 15, 2015. REUTERS/Lucy Nicholson
Donald Trump speaks about the results of Super Tuesday primary and caucus voting at a news conference in Palm Beach, Florida, March 1, 2016. REUTERS/Scott Audette
A Chinese Coast Guard ship (top) near a Vietnam Marine Guard ship in the South China Sea, about 210 km (130 miles) off Vietnam, May 14, 2014. REUTERS/Nguyen Minh
Senator Marco Rubio speaks with reporters after a campaign town hall at the Omar Shrine Temple in Mount Pleasant, South Carolina, February 17, 2016. REUTERS/Chris Keane
Donald Trump speaks at a campaign rally at Valdosta State University in Valdosta, Georgia, February 29, 2016. REUTERS/ Philip Sears
Comedian Chris Rock hosts the 88th Academy Awards in Hollywood, California, February 28, 2016. REUTERS/Mario Anzuoni