Demonstrators throw fire bombs to riot police during violent protests in central Athens February 12, 2012. (Photo by Milos Bicanski/Getty Images)

A subway worker walks away after a train departed the station in central Pyongyang, North Korea May 7, 2016. (Photo by Damir Sagolj/Reuters)

A jogger runs on the bank of Donaukanal channel in central Vienna, Austria, September 5, 2016. (Photo by Heinz-Peter Bader/Reuters)

In this August 1, 2014 photo provided by the National Park Service are male caribou antlers in the Oolah Valley, likely the result of a grizzly kill as he migrated south for the winter at the Arctic National Park and Preserve in Alaska. The nation's northernmost national park says its new management plan will have to consider the effects of a new industrial road to the mining district of Ambler, the first road that would be constructed within its Maryland-sized boundaries. (Photo by Cadence Cook/AP Photo/National Park Service)

A leaflet denouncing South Korean President Park Geun-hye lies on the ground after it was torn at a protest calling Park to step down, in Seoul, South Korea, November 19, 2016. (Photo by Kim Hong-Ji/Reuters)

A woman walks in central Rason city, northeast of Pyongyang, August 29, 2011. (Photo by Carlos Barria/Reuters)

People cross the street in central Pyongyang, North Korea May 4, 2016. (Photo by Damir Sagolj/Reuters)

A girl reacts during a rehearsal for the Independence Day military parade in central Kiev, Ukraine, August 19, 2016. (Photo by Valentyn Ogirenko/Reuters)