North Korea and the nuclear security summit focusing on the issue of the Islamic State

U.S. President Barack Obama will speak Friday at the end of the second and final day of the nuclear security summit in Washington attended by world leaders.

The U.S. leader said Thursday that in the wake of attacks in places including Brussels, there is “not only great urgency around the nuclear issue but eliminating generally the scourge of terrorism.”

Obama’s fourth and final nuclear summit has come at a time of heightened concern about the possibility that Islamic State militants could set off radioactive bombs, and also about North Korea’s nuclear weapons development.

At a State Department ministerial level dinner, Secretary of State John Kerry said there have been times when nuclear security progress has been slow, and there remains an “enormous amount more to do. But every step forward that we take is a step away from danger."

Earlier Thursday, Obama held a series of meetings with leaders. He met with South Korean President Park Geun-hye and Japanese Prime Minister Shinzo Abe to discuss the North Korean threat following Pyongyang's January nuclear test and a long-range missile launch in February.

Pyongyang also was among the focal points when Obama sat down later with Chinese President Xi Jinping.

"We want to enhance communication and coordination on the Korean nuclear issue and other regional and global issues," said Xi at the start of the talks.

Washington views Beijing, Pyongyang's ally, as key in enforcing U.N. sanctions against North Korea for its weapons development.