The U.S. says it will discuss North Korean and Iranian nuclear issues at an April nuclear summit in Washington.

National Security Council spokesman Mike Hammer said during a news briefing at the Foreign Press Center on Friday, local time, that the North Korean and Iranian nuclear issues were a major focus of President Barack Obama’s first year in office.

Hammer said he hopes North Korea will understand that the only way to avoid isolation is to return to the six-party talks.

He also said that Washington has a blueprint for its North Korea policy and knows what it needs to do to resolve the North Korean nuclear issue. However, he added that the U.S. also understands that it takes time to encourage another country to change its behavior.

Hammer said the two-day summit, opening April eleventh, is a follow-up to a pledge Obama made last April in Prague to seek nonproliferation and eventual global disarmament of nuclear weapons.