Bangladeshi fisherman feed their otters as they catch fish in Narail some 208 kms from Dhaka on March 11, 2014. The fishermen are using a rare technique that relies on coordination between man and trained otters, a centuries-old fishing partnership that has already long died out in other parts of Asia. (Photo by Munir Uz Zaman/AFP Photo)

A Polish Army tank takes part in the NATO Noble Jump exercise on a training range near Swietoszow Zagan, Poland, Thursday, June 18, 2015. (AP Photo/Alik Keplicz)

A mine detection rat is given banana as a reward after successfully identifying an inactive mine on July 2, 2015 in Siem Reap, Cambodia. The Cambodian Mine Action Center (CMAC) working with the Belgian NGO APOPO has recently begun testing the feasability of using large mine detection rats from Tanzania to help clear fields of mines and unexploded ordnance in one of the most bombed and mined countries in the world. (Photo by Taylor Weidman/Getty Images)

Devotees try to form a human pyramid to break a clay pot containing curd during celebrations to mark the Hindu festival of Janmashtami in Mumbai, India, September 6, 2015. Janmashtami, which marks the birthday of Hindu god Krishna, is being celebrated across the country today. (Photo by Danish Siddiqui/Reuters)

Members of the Communist New Fourth Army on parade. Note how the modern equipment contrasts with the shoeless soldiers in the foreground. (Photo by Hulton Archive/Getty Images). 6th July 1946

A youth dives into a crater filled with water in Aleppo's al-Shaar district, in this July 10, 2014 file photo. (Photo by Hosam Katan/Reuters)

Mount Sinabung volcano erupts, as seen from Tiga Pancur village, Karo Regency in Indonesia's North Sumatra province, in this October 8, 2014 file photo. (Photo by Y. T. Haryono/Reuters)

A man carries a smoke flare as far-right activists march during the Gay Pride parade on June 12, 2016 in Kiev. More than 700 gay rights activists marched through central Kiev on June 12 amid a massive police presence for the third such gay pride event in the ex-Soviet country where homophobia remains widespread. The June 12 march was the first ever gay pride rally to be held in central Kiev, prompting an unprecedented security operation with several thousand police and National Guard officers lining the route during the event, which lasted around 20 minutes. (Photo by Yuriy Kirnichny/AFP Photo)