A bunker at aformer Swiss artillery fortress called Heldsberg stands near the town of St. Margareten, Switzerland March 22, 2015. Heldsberg fortress, located on the Swiss-Austrian border near the River Rhine and Lake Constance was built from 1938 to 1940 and remained in military use until 1992. Since 1993 it is open to the public as Fortress Museum Heldsberg. (Photo by Arnd Wiegmann/Reuters)

An employee walks near a rotary dredge which works on the coal face of the Borodinsky opencast colliery, near the Siberian town of Borodino, east of Krasnoyarsk, December 9, 2014. The Borodinsky colliery, 9 km (5.6 miles) long and more than 100 meters (328 feet) deep, annually produces more than 20 million tons of coal and is considered to be the biggest opencast coal mine in Russia, according to official representatives. (Photo by Ilya Naymushin/Reuters)

The camera rolls as actors dressed as historical Chinese soldiers act as though they have been hit by artillery, during filming of “The Last Prince” television series on location near Hengdian World Studios near Hengdian July 24, 2015. Hundreds of well-trained actors and other professionals are available at the Hengdian World Studios. The well-organised team coordinate complicated battle scenes to satisfy the huge appetite for productions about the war against Japan. (Photo by Damir Sagolj/Reuters)

Master Sergey Suprun uses a portable radio set as he stands near a rotary dredge which works on the coal face of the Borodinsky opencast colliery, near the Siberian town of Borodino, east of Krasnoyarsk, Russia October 27, 2015. The Borodinsky colliery, 9 km (5.6 miles) long and more than 100 meters (328 feet) deep, annually produces more than 20 million tons of coal and is considered to be the biggest opencast coal mine in Russia, according to official representatives. (Photo by Ilya Naymushin/Reuters)

A policeman stands near a burning vehicle during clashes between supporters of former prime minister Imran Khan and riot police near Khan's house to prevent officers from arresting him, in Lahore on early March 15, 2023. Pakistan police appeared on March 15 to have given up an attempt to arrest former prime minister Imran Khan, ending a siege of his residence after violent clashes with hundreds of his supporters. (Photo by Arif Ali/AFP Photo)

Ice covered leafs are pictured on a tree near Amstall in northern Austria, December 2, 2014. Freezing fog and rain covered parts of the region with ice, causing blocked roads due to fallen trees and closed schools for security reasons, local media report. (Photo by Heinz-Peter Bader/Reuters)

Pro-Russian rebels stand near a monument during a ceremony to honour the World War Two defenders of Donetsk from Nazi forces, in Donetsk, in this September 8, 2014 file photo. (Photo by Marko Djurica/Reuters)

Participants cross cold and muddy waters during the Strong Race competition near Tukums May 4, 2014. About 6500 people competed in this extreme running race, which includes cross-country running, elements of agility and power discipline. (Photo by Ints Kalnins/Reuters)