An Army Sikorsky VH-34s Choctaw helicopter once used to transport President Dwight D. Eisenhower sits in a field at the 309th Aerospace Maintenance and Regeneration Group boneyard Thursday, May 14, 2015 at Davis-Monthan Air Force Base in Tucson, Ariz. President Eisenhower became the first chief executive to be transported by helicopter. Presidents Eisenhower and John F. Kennedy were transported in VH-34 helicopters and VH-34's served as “Army One” from 1958 through 1963. (Photo by Matt York/AP Photo)

Romanian soldiers take part in a joint military exercise with NATO members, called “Agile Spirit 2015” at the Vaziani military base outside Tbilisi, Georgia, July 21, 2015. Georgian soldiers along with U.S. marines and platoon-size units from Bulgaria, Latvia, Lithuania and Romania are taking part in the exercises at the Vaziani military base outside Tbilisi. (Photo by David Mdzinarishvili/Reuters)

Militant Islamist fighters take part in a military parade along the streets of Syria's northern Raqqa province June 30, 2014. The fighters held the parade to celebrate their declaration of an Islamic “caliphate” after the group captured territory in neighbouring Iraq, a monitoring service said. The Islamic State, an al Qaeda offshoot previously known as Islamic State in Iraq and the Levant (ISIL), posted pictures online on Sunday of people waving black flags from cars and holding guns in the air, the SITE monitoring service said. (Photo by Reuters/Stringer)

A student attending a winter military camp reacts during a training session in Ansan, south of Seoul January 3, 2013. Hundreds of students between 11 and 17 years old attend winter boot camp training courses every year. The winter courses range from 4 to 14 days at the Blue Dragon Camp run by retired marines, which also offers summer boot camp for students. (Photo by Kim Hong-Ji/Reuters)

A bus goes through a flooded area in Jiujiang, Jiangxi Province, China, June 19, 2016. A week of torrential rain in southern China has killed dozens of people and forced relocation of tens of thousands of residents, media reported. (Photo by Reuters/China Daily)

A man carries a bag on his back in Guangzhou, Guangdong province, January 26, 2016. According to traffic police, over 2.9 billion trips will be made around China during the 40-day Spring Festival travel rush, which started on January 24. (Photo by Reuters/Stringer)

Young Chinese football players help an injured player off the field during training at the Evergrande International Football School on June 12, 2014 near Qingyuan in Guangdong Province, China. The sprawling 167-acre campus is the brainchild of property tycoon Xu Jiayin, whose ambition is to train a generation of young athletes to establish China as a football powerhouse. The school is considered the largest football academy in the world with 2400 students, more than 50 pitches and a squad of Spanish coaches through a partnership with Real Madrid. (Photo by Kevin Frayer/Getty Images)

In this photo taken on Wednesday, January 9, 2013, ahead of the Chinese lunar new year of the Snake, following the Chinese zodiac, genetically modified, auspicious, white snakes slither across the altar at the Temple of White Snakes in Taoyuan county, in north western Taiwan. Director of the temple Mr. Lo Chin-shih says the new year of the snake would be a time of steady progress, in contrast to the more turbulent nature of the outgoing year of the dragon. The Chinese new year fall on February 10. (Photo by Wally Santana/AP Photo)