The launch of four ballistic missiles by the Korean People's Army (KPA) during a military drill at an undisclosed location in North Korea, March 7, 2017. (KCNA/STR/AFP/Getty Images)
A satellite image shows what CSIS Asia Maritime Transparency Initiative says appears to be concrete structures with retractable roofs on the artificial island Fiery Cross reefs in the South China Sea in this image taken February 7, 2017 and released on Fe
US Defense Secretary James Mattis (L) and Japanese Prime Minister Shinzo Abe (R) shake hands at the prime minister's office in Tokyo on February 3, 2017. (EUGENE HOSHIKO/AFP/Getty Images)
A soldier of the Polish Army sits in a tank as a NATO flag flies behind during the NATO Noble Jump military exercises of the VJTF forces on June 18, 2015 in Zagan, Poland. (Sean Gallup/Getty Images)
Prime Minister of Israel Benjamin Netanyahu speaks to U.S. President Barack Obama during a bilateral meeting at the Lotte New York Palace Hotel, September 21, 2016 in New York City. (Drew Angerer/Getty Images)
Three A-10 Thunderbolt II aircraft fly in formation over Tucson, Ariz., during an air refueling training mission, April 14, 2006. (Senior Airman Christina D. Ponte/DefenseLINK/Released)