A bomb-laden Su-25 jet at the Hmeimim air base in December 2015. Russia's lease agreement obliged Assad’s military to safeguard the perimeter of the Hmeimim base, while giving Moscow legal jurisdiction over the facilities inside. Negotiating perimeter protection from Syria’s new rulers will be vital for the Russian bases in an era of wire-controlled drones immune to jamming. (Photo by AP Photo)

Team Strong Silvers member Ngai Hin Kwok, 66, works out as teammate Ng Siu Chi, 57, watches at a stadium in Singapore March 15, 2015. Team Strong Silvers, is a group of senior citizens who train in calisthenics. The trio trains individually at least three times a week, and meets up for joint calisthenics at least twice a month. (Photo by Edgar Su/Reuters)

People look at French artist Clement Briend's photographic light installation “Divine Trees”, which features images of divine figures highly revered in Asian cultures projected on trees towering over bystanders, during a media preview of the Singapore Night Festival in Singapore August 21, 2014. The Singapore Night Festival begins on Friday. (Photo by Edgar Su/Reuters)

A combination photo shows various popular street foods under $6 from various hawker food stalls and eateries in Singapore, taken between July 28 to 31, 2016. Top row (L to R) bak chor mee, soya sauce chicken; Middle row (L to R) laksa, hokkien mee, nasi lemak, ice kachang; Bottom row (L to R) rojak, roti prata and satay. (Photo by Edgar Su/Reuters)

A young man leaps across stellae at the Memorial to the Murdered Jews of Europe, also called the Holocaust Memorial, on January 26, 2012 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Rapper Cardi B is seen in Paris, France on September 30, 2019 at Paris Fashion Week. (Photo by Splash News and Pictures)

Women are reflected in a puddle as they walk across Red Square in Moscow, Russia on April 26, 2018. (Photo by Yuri Kadobnov/AFP Photo)

Santa Students practice dancing during the Charles W. Howard Santa Claus School workshop on October 16, 2008 in Midland, Michigan. (Photo by Al Bello/Getty Images)