A German 'Tornado' fighter aircraft prepares to land at Bchel air base on February 27, 2019 near Cochem, Germany. (Photo by Thomas Lohnes/Getty Images)Soldiers drive an ATV into a Chinook CH-47 at Avalon Airport on March 01, 2019 in Melbourne, Australia during the 2019 Australian International Airshow. (Photo by Michael Dodge/Getty Images)Yemeni soldiers man turrets in pickup trucks lining-up during a graduation ceremony for a new batch of cadets in the northwestern city of Saada on March 2, 2019, in a show of support against the Saudi-led intervention in the country. (AFP/Getty Images)Fighter Jets get refuelled above Avalon Airport on March 01, 2019 in Melbourne, Australia during the 2019 Australian International Airshow. (Photo by Michael Dodge/Getty Images)The Ticonderoga-class guided-missile cruiser USS Chancellorsville (CG 62) fires its 5-inch gun during a live-fire gunnery exercise. Chancellorsville is forward-deployed to the U.S. 7th Fleet area of operations in support of security and stability in the Indo-Pacific region. (MC2 Jeremy Graham/Navy)South Korean army soldiers participate in a military exercise in Yeoncheon, South Korea, near the border with North Korea, Wednesday, Feb. 27, 2019 during President Donald Trump's second meeting with North Korean leader Kim Jong Un aimed at getting Kim to give up nuclear weapons in exchange for relief from sanctions hobbling his economy and better relations with the U.S. and other nations. (AP Photo/Ahn Young-joon)MI-17V-5 helicopter during rehearsals for the upcoming Army Day in Kathmandu, Nepal on March 1, 2019. (PRAKASH MATHEMA/AFP/Getty Images)In this Wednesday, Feb.27, 2019 file photo, Indian army soldiers arrive at the wreckage of an Indian helicopter after it crashed killing several in the Budgam area, on the outskirts of Srinagar, Indian controlled Kashmir. This week's standoff between India and Pakistan is their latest in a long dispute over the divided Himalayan region of Kashmir, dating back to their independence in 1947. (AP Photo/Mukhtar Khan)A female cadet sits in an aircraft cockpit simulator during a class at the Krasnodar Higher Military Aviation School in Krasnodar, Russia on March 1, 2019. (VITALY TIMKIV/AFP/Getty Images)