U.S. President Barack Obama holds a closing news conference at the Nuclear Security Summit in Washington, D.C

U.S. President Barack Obama holds a closing news conference at the Nuclear Security Summit in Washington, D.C. Obama says that over the preceding six years global leaders have made significant progress in securing nuclear materials so that they do not fall into the hands of terrorists. He answers questions about U.S. drone strikes against terrorists in Iraq and Syria, Iran's nuclear program, U.S. and Russian nuclear arms reductions, nuclear proliferation, press freedom in Turkey, and the 2016 presidential election.