People mourn at the Tsitsernakaberd Armenian Genocide Memorial Museum in Yerevan, April 21, 2015 (Photo: Reuters)
Wild bluebells form a carpet in the Hallerbos, also known as the "Blue Forest", near the Belgian city of Halle April 21, 2015. The forest is known for its flowers which bloom around mid-April, turning the forest completely blue (Photo: Reuters)
A follower of the Houthi group raises his weapon as he stands on a vehicle on a damaged street, caused by an April 20 air strike that hit a nearby army weapons depot, in Sanaa April 21, 2015 (Photo: Reuters)
Smoke is seen at a damaged street, caused by an April 20 air strike that hit a nearby army weapons depot, in Sanaa April 21, 2015 (Photo: Reuters)
The Solar Impulse 2 plane is seen after taking off to Nanjing in Jiangsu province, at the Chongqing Jiangbei International Airport, April 21, 2015 (Photo: Reuters)
Two tourists feed a duck in a pond at Keukenhof, known as the Garden of Europe, a spring park with approximately seven million flower bulbs, in Lisse, Netherlands, Tuesday, April 21, 2015 (Photo: AP)
A tourist takes pictures of blossoming tulips at Keukenhof, known as the Garden of Europe, a spring park with approximately seven million flower bulbs, in Lisse, Netherlands, Tuesday, April 21, 2015 (Photo: AP)
South Korea's President Park Geun-hye (L) shakes hands with Peru's President Ollanta Humala in front of a new KT-1P training aircraft produced in Peru with South Korean technology, at Las Palmas Lima's military airbase, April 21, 2015 (Photo: Reuters
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President Barack Obama speaks on the South Lawn of the White House in Washington, Tuesday, April 21, 2015 (Photo: AP)
A rower is seen on the River Thames as the sun rises in Henley-on-Thames, southern England April 21, 2015 (Photo: Reuters)