Swiss police officers stand beside of mock gates of the NEAT Gotthard Base Tunnel inside the event hall for the upcoming opening ceremony near the town of Erstfeld, Switzerland May 31, 2016. The celebrations of the opening of the Gotthard Base Tunnel will start on June 1, 2016. With a length of 57 km (35 miles) crossing the Alps, the Gotthard Base tunnel is the world's longest train tunnel. (Photo by Arnd Wiegmann/Reuters)

A breeder puts a giant panda cub into a crib at Chengdu Research Base of Giant Panda Breeding in Chengdu, Sichuan province, September 23, 2013. Fourteen new joiners to the 128-giant-panda-family at the base were shown to the public on Monday, according to local media. (Photo by Reuters/China Daily)

Ice sculptures based on the caracters by Walt Disney are shown at the snow and ice sculpture festival on December 15, 2011 in Brugge, Belgium. (Photo by Mark Renders/Getty Images)

Yaks head towards the Everest base camp in Solukhumbu District April 28, 2014. (Photo by Navesh Chitrakar/Reuters)

Smoke and flames rise over a warehouse storing ammunition for multiple rocket launcher systems at a military base in the town of Kalynivka in Vinnytsia region, Ukraine September 27, 2017. Ukrainian officials say they have evacuated more than 30,000 people after a fire and ammunition explosions, at the military base on Tuesday. (Photo by Gleb Garanich/Reuters)

“Pearl Harbor, known to Hawaiians as Puʻuloa, is a lagoon harbor on the island of Oʻahu, Hawaiʻi, west of Honolulu. Much of the harbor and surrounding lands is a United States Navy deep-water naval base. It is also the headquarters of the U.S. Pacific Fleet. The attack on Pearl Harbor by the Empire of Japan on December 7, 1941, brought the United States into World War II”. – Wikipedia

Photo: Women fire fighters directing a hose after the Japanese attack on the US naval base at Pearl Harbour (Pearl Harbor). (Photo by Three Lions)

Iraqi soldiers work at a radio station at Makhmour base, Iraq April 17, 2016. The Iraqi army has set up a radio station at its base in Makhmour broadcasting into areas south of Mosul controlled by Islamic State militants. The radio, which reaches villages halfway to the northern city, broadcasts military anthems and messages to the more than one million civilians living there. Radio operators said their aim was to weaken the militants’ morale and reassure civilians that the military has not forgotten them after nearly two years under Islamic State control. (Photo by Ahmed Jadallah/Reuters)

Civilians are led by members of pro-Russian self-defence units as they run outside a military base during an assault in the Crimean town of Belbek near Sevastopol March 22, 2014. Russian troops forced their way into a Ukrainian airbase in Crimea with armored vehicles, automatic fire and stun grenades on Saturday, injuring a Ukrainian serviceman and detaining the base's commander for talks. (Photo by Vasily Fedosenko/Reuters)