A Chinese woman wears a mask to protect from particles blown in during a sandstorm as she walks in the street on May 4, 2017 in Beijing, China. Sandstorms are common in northern China during the spring season and are caused when heavy winds from Mongolia in the north brings sand and pollutants that can blanket Chinese cities and cause air quality to deteriorate. (Photo by Kevin Frayer/Getty Images)

Chinese soldiers leave after Chinese President Xi Jinping inspected troops of People's Liberation Army (PLA) Hong Kong Garrison at the Shek Kong Barracks in Hong Kong, Friday, June 30, 2017. Xi landed in Hong Kong Thursday to mark the 20th anniversary of Beijing taking control of the former British colony, accompanied by a formidable layer of security as authorities showed little patience for pro-democracy protests. (Photo by Kin Cheung/AP Photo)

A military AWAC aircraft lands at the British RAF Akrotiri airbase on March 20, 2011 in Cyprus. Defence analysts said the sovereign military airfield at Akrotiri could be used by the RAF to help enforce a no-fly zone over Libya against Col Gaddafi’s offensive against outgunned Libyan rebels. (Photo by Matt Cardy/Getty Images)

A female member of the Ahbab Al-Mustafa Battalion holds a gun as she undergoes military training in Aleppo's Salaheddine district, June 24, 2013. (Photo by Muzaffar Salman/Reuters)

A girl walks past a destroyed mosque in the town of Mararaba, after the Nigerian military recaptured it from Boko Haram, in Adamawa state May 10, 2015. (Photo by Akintunde Akinleye/Reuters)

A girl shoots a gun armed with blanks at an weapon exhibition during a military show in St.Petersburg, Russia, Saturday, October 14, 2017. (Photo by Dmitri Lovetsky/AP Photo)

A helicopter from the Venezuela's Army takes part in a military parade to celebrate the 207th anniversary of Venezuela's independence in Caracas, Venezuela July 5, 2018. (Photo by Marco Bello/Reuters)

Drinking from a helmet at a graduation ceremony held by the Military University of the Russian Defence Ministry at Moscow's Victory Park in Moscow, Russia on June 15, 2019. (Photo by Gavriil Grigorov/TASS)