Susan Walsh / AP
President Barack Obama speaks at Hankuk University in Seoul, South Korea, March 26, 2012. Obama discussed his Prague agenda to stop the spread of nuclear weapons and seek the peace and security of a world without them.
Updated 10:20 p.m. ET: President Barack Obama said on Monday the United States can further reduce its nuclear weapons stockpile while maintaining its strategic deterrent.
Obama, speaking at a university in Seoul ahead of global nuclear security summit, said he plans to raise the issue of arms control with Russian President-elect Vladimir Putin when they meet in May.
The president urged North Korean leaders to "have the courage to pursue peace" and warned the country that provocation will not lead to rewards, but to condemnation by the international community. "Those days are over. This is the choice before you," he told students in Seoul.
Obama also said that time was running out to resolve Iran's nuclear standoff with the west.
Tehran says its nuclear program is purely peaceful, but Israel and Western nations believe it is moving towards a nuclear bomb that could change the regional balance of power.
"Once again, there is the possibility of a diplomatic resolution that gives Iran access to peaceful nuclear energy while addressing the concerns of the international community," Obama told students in Seoul.
"Today, I'll meet with the leaders of Russia and China as we work to achieve a resolution in which Iran fulfills its obligations."
President Obama visited the demilitarized zone between North and South Korea and said China should rein in its communist neighbor. NBC's Kristen Welker reports.
Obama will rely on China to work with North Korea, the Washington Post reported. The president has called nuclear terrorism the United States’ biggest threat, according to the Post, and North Korea could prove to be a grave issue.