A Russian S-400 anti-aircraft missile system is displayed at the exposition field in Kubinka's Patriot Park outside Moscow on Aug. 22, 2017. (Alexander Nemenov/AFP/Getty Images)
U.S. Secretary of Defense James Mattis arrives for a press conference at the Australia-U.S. Ministerial Consultations in Stanford, California, on July 24. (Photo by Justin Sullivan/Getty Images)
Afghan Shiite mourners offer funeral prayers for nine victims, who were killed in a suicide attack the previous day, in Kabul on August 16, 2018. NOORULLAH SHIRZADA/AFP/Getty Images
French President Emmanuel Macron and U.S. President Donald Trump look at members of the Fifth Regiment de Cuirassiers ride by in tanks as they attend the annual Bastille Day military parade on the Champs-Elysees avenue in Paris on July 14, 2017. JOEL SAGET/AFP/Getty Images
Former Director of the U.S. Central Intelligence Agency John Brennan testifies before the House Permanent Select Committee on Intelligence in Washington, D.C. on May 23, 2017. (Drew Angerer/Getty Images)
U.S. President Donald Trump and Turkish President Recep Tayyip Erdogan deliver joint statements at the White House on May 16, 2017. (Michael Reynolds-Pool/Getty Images)
U.S. President Donald Trump speaks with Alan B. Norman, director and chief test pilot, and Marillyn A. Hewson, the chairman, president, and chief executive officer of Lockheed Martin, next to an F-35 at the White House on July 23. (Photo by Brendan Smialowski / AFP)
U.S. Vice President Mike Pence announces the Trump administration's plan to create the U.S. Space Force by 2020 during a speech at the Pentagon August 9, 2018 in Arlington, Virginia. Photo by Chip Somodevilla/Getty Images
U.S. Vice President Mike Pence delivers opening remarks during the National Space Council's first meeting at the Smithsonian National Air and Space Museum's Steven F. Udvar-Hazy Center on October 5, 2017. (Photo by Joel Kowsky/NASA via Getty Images)
Russian President Vladimir Putin speaks with his Syrian counterpart, Bashar al-Assad, during their meeting in Sochi, Russia, on May 17. (Mikhail Klimentyev/AFP/Getty Images)
Flag draped transfer cases with the remains of American soldiers repatriated from North Korea are seen during a ceremony after arriving to Joint Base Pearl Harbor-Hickam, Honolulu, Hawaii, on August 1, 2018. RONEN ZILBERMAN/AFP/Getty Images
A firing line of Syrian Democratic Forces soldiers take aim and fire at targets during a marksmanship training exercise to prepare for Operation Roundup, an SDF-led campaign to clear the last Islamic State strongholds, near Shaddadi, Syria, on May 27. (Staff Sgt. Timothy R. Koster/U.S. Army)
A group of U.S. soldiers keeps an eye on the demarcation line during a security patrol outside Manbij, Syria, on June 24. (U.S. Army photo by Staff Sgt. Timothy R. Koster)
U.S. Secretary of Defense Jim Mattis speaks to the media prior to hosting an Honor Cordon for His Excellency Yusuf bin Alawi, Oman's Minister Responsible for Foreign Affairs. (Photo by Mark Wilson/Getty Images)
