Two F-15E Strike Eagles wait to receive fuel from a KC-135R Stratotanker during exercise Red Flag 15-1 on their way to Nellis Air Force Base, Nev., Jauary 23, 2015. The F-15s are assigned to the 4th Fighter Wing. U.S. (Photo by Airman 1st Class Aaron J. Jenne/Reuters)

A rickshaw driver looks out the windshield as he drives onto the highway in Mardan, Pakistan January 30, 2017. (Photo by Fayaz Aziz/Reuters)

Deers walk past Indonesia's honour guard as they wait for the arrival of Saudi Arabia's King Salman bin Abdul Aziz at the presidential palace in Bogor on March 1, 2017. Cheering crowds welcomed King Salman on March 1 as he began the first visit by a Saudi monarch to Indonesia for almost 50 years, seeking stronger economic ties with the world's most populous Muslim-majority country. (Photo by Adek Berry/AFP Photo)

Stray dogs stand on tombs in Diamond Hill cemetery in Hong Kong, China, 04 April 2017. According to the lunar calendar, the Qingming Festival is observed on 04 April . The Qingming Festival, also known as Tomb-Sweeping Day, is marked by Chinese people by going to the cemetery to cleaning up tombs, bring flowers, and making offerings to their ancestors. (Photo by Jerome Favre/EPA)

Turkana tribesmen walk with guns to protect their cattle from rival tribes near Baragoy, Kenya August 4, 2017. (Photo by Goran Tomasevic/Reuters)

A hogweed bonking beetle and yellow dung fly in a stalk standoff (the fly gave in), in Burley-in-Wharfedale, Yorkshire, England. (Photo by Rebecca Cole/Alamy Stock Photo)

In this aerial file photo taken on Tuesday, October 31, 2017, a woman walks past a statue of Soviet Union founder Vladimir Lenin at the Russian leased Baikonur cosmodrome, in Kazakhstan. The thousands of statues of Vladimir Lenin spread across the vast region bring to mind poet Vladimir Mayakovsky's ringing line of devotion: “Lenin lived, Lenin lives, Lenin will live”. (Photo by Dmitri Lovetsky/AP Photo)

A Pegasus airplane is seen stuck in mud as it skidded off the runway after landing in Trabzon Airport, Turkey early Sunday on January 14, 2018. A passage plane which belongs to Turkey's Pegasus Airlines skidded off the runway of Trabzon airport Saturday and ended up halfway down a steep slope into the Black Sea, Turkish media reported on Sunday. 162 passengers and crew on board were safely evacuated. (Photo by Hakan Burak Altunoz/Anadolu Agency/Getty Images)