Washington DC, Apr 01 (ANI): Prime Minister Narendra Modi on Friday departed from Washington D.C. where he attended the Nuclear Security Summit 2016. He will reach Riyadh in Saudi Arabia as a part of his three-nation tour. Leaders of more than 50 countries attended the fourth and final Nuclear Security Summit, which was started in 2010 as an initiative by U.S President Obama with the aim of preventing nuclear materials from falling into the hands of terrorists.