A drone (L) and a violet smoke are seen as Bulgaria's soldiers take part in a joint military drill "Peace Sentinel 2017" with US and Serbian army at Koren military training ground, South East Bulgaria on July 15, 2017. (DIMITAR DILKOFF/AFP/Getty Images)
US forces salute Captain Nancy S. Lacore (not seen) during a handover ceremony at the Camp Lemonier US navy base in Djibouti on July 20, 2017. Captain Lacore is the first woman captain to be in charge of the overall command of Camp Lemonier. (HOUSSEIN HERSI/AFP/Getty Images)
A Russian SU-27 fighter performs during an exhibition flight at the annual air show MAKS 2017 in Zhukovsky, some 40kms outside Moscow on July 20, 2017. (MAXIM ZMEYEV/AFP/Getty Images)
Colombian army commandos take part in a military parade to celebrate the 207th nniversary of the independence, in Bogota, on July 20, 2017. (LUIS ACOSTA/AFP/Getty Images)
U.S. President Donald Trump and Vice President Mike Pence listen to Secretary of Defense Jim Mattis as Trump about to greet service members after a meeting at the Pentagon July 20, 2017 in Arlington, Virginia. President Trump participated in a 'Pol-Mil session' and was briefed on national security issues and the fight against ISIS. (Alex Wong/Getty Images)
A green shirt 'Hook Runner' crew member looks on before the launch of Super Hornet aircraft on July 14, 2017 in Townsville, Australia. USS Ronald Reagan is a 1,092- foot aircraft carrier which carries a crew of 4,539 around 60 aircraft. Exercise Talisman Sabre is the largest combined military exercise undertaken in Australia. The biennial exercise is the principal Australian and U.S. military training activity. (Ian Hitchcock/Getty Images)
A Red Arrows display before the Formula One Grand Prix of Great Britain at Silverstone on July 16, 2017 in Northampton, England. (Dan Mullan/Getty Images)
A soldier with the Afghan National Army (ANA) cleans his weapon at an outpost in the Momand Valley on July 16, 2017 in Achin District, Afghanistan. The building was previously used as of a jail by the Islamic State of Iraq and Syria - Khorasan (ISIS-K) and was taken by Afghan Commandos nine days prior. Operations are currently underway to remove ISIS fighters from Nangarhar Province in Eastern Afghanistan. (Andrew Renneisen/Getty Images)
Russian President Vladimir Putin delivers looks on during the opening ceremony of the MAKS 2017 air show in Zhukovsky, outside Moscow on July 18, 2017. (SERGEI KARPUKHIN/AFP/Getty Images)
U.S. Army soldiers look on while NATO paratroopers drop out of a US Air Force Hercules during the 'Swift Response 17' joint airborn military exercise at Bezmer airfield near the village of Bezmer on July 18, 2017. The U.S.-led 'Swift Response 17' airborne exercise, part of the multinational 'Saber Guardian 2017' exercise, involves up to 1,600 soldiers from the United States, Canada, Italy, Portugal and Greece. (DIMITAR DILKOFF/AFP/Getty Images)
Divers from the Royal Navy and the British Sub-Aqua Club are recovering two Highball bouncing bombs from Loch Striven on July 19, 2017 in Loch Striven,Scotland. More than two hundred of the spherical bombs were tested on the Loch on the Glenstriven Estate on the Argyll peninsula during World War Two. Highball was the military codename for the weapons, a naval version of the "Upkeep" bouncing bombs used in the Dambusters raid in May 1943. (Jeff J Mitchell/Getty Images)
In a propaganda film posted to the Taliban's official website, a fighter can be seen carrying a FN SCAR 7.62mm rifle, a weapon commonly issued to U.S. special operators, such as Marine Raiders and Army Rangers. (Screen shot from “Omari Army 5,” an Al Emrah Studio production)