North Korea nuclear envoy to visit U.S. SEOUL, South Korea - In another sign of warming relations between two wartime foes, a senior North Korean nuclear negotiator will attend a security conference in the United States, a U.S. official confirmed Thursday. Word of Ri Yong Ho's visit to the forum held by Syracuse University comes on the heels of a breakthrough agreement that will provide much-needed U.S. food aid to North Korea in exchange for a rollback of its nuclear programs. The agreement announced Wednesday sets in motion a plan laid out by North Korean leader Kim Jong Il before his death in December: to improve relations with the U.S. and to get back to six-nation disarmament-for-aid negotiations. Significant challenges remain, however, in achieving the long-term goal of the U.S. and other nations: to persuade Pyongyang to end its nuclear ambitions altogether. N. Korea agrees to suspend nuclear activities Kim Jong Un issues threat before U.S.-S. Korea drills First, diplomats need to iron out the tricky logistics of distributing, and monitoring, the 240,000 metric tons of U.S. food aid earmarked for hungry North Korean children. They also need to work out a timeline for the return of U.N. nuclear inspectors tasked with verifying whether Pyongyang sticks to its promises. And while the deal paves the way for unprecedented exchanges with the U.S., North Korea still must confront the complicated matter of improving relations with rival South Korea, still smarting from two deadly incidents in 2010 that Seoul blames on Pyongyang. The commander of U.S. forces in the Pacific, Adm. Robert Willard, said Thursday he is hopeful but not optimistic about the latest efforts to get North Korea to end its nuclear weapons program. "In the past we have not seen much change," Willard told a congressional hearing in Washington. Still, there was cautious hope that North Korea's relations with the U.S. and its allies have turned a corner after years of tensions. The agreement calls on Pyongang to suspend uranium enrichment and place a moratorium on nuclear and long-range missile tests. In a possible sign of things to come, Ri, North Korea's vice foreign minister and envoy to nuclear disarmament negotiations, has been cleared to travel to the U.S. to attend the Syracuse University forum, The Associated Press was told in Seoul. While Syracuse University's Maxwell School of Citizenship and Public Affairs will hold the forum, its exact location was not known. U.S. State Department spokeswoman Victoria Nuland said the envoy was coming at the Maxwell School's invitation for three days next week to attend "track two," or unofficial discussions the school is sponsoring, starting Wednesday. "At the current moment there are no plans for official U.S. government meetings with the negotiator," she told a news briefing in Washington. The U.S. and North Korea do not have formal diplomatic relations, but the measures laid out in the deal announced Wednesday include facilitating "people-to-people" exchanges. The deal is a sign that the foreign policy laid out in the final years of Kim Jong Il's rule - with improved relations with the U.S. as a key goal - will be carried out by his young son. Shortly before Kim Jong Il's death was announced, the AP reported that a deal similar to the one announced this week was imminent. A return to negotiations before the end of the semiofficial 100-day mourning period suggests stability and continuity during the closely watched transition of leadership in North Korea. In Pyongyang, a spokesman for North Korea's Foreign Ministry told the state-run Korean Central News Agency that the steps are confidence-building measures designed to improve relations between North Korea and the U.S. The U.S. and North Korea fought on opposite sides of the Korean War and signed an armistice to end the fighting in 1953. They have never signed a peace treaty, and the U.S. has some 28,000 troops protecting ally South Korea. The agreement announced Wednesday was finalized last week during talks in Beijing. It opens the way for international inspections for the North's nuclear program, which has gone unmonitored for years. Nuland said that the U.S. was now looking to North Korea to invite the International Atomic Energy Agency "to verify that all the steps we have agreed upon" are being implemented. Outsiders have been watching how Kim Jong Un, believed to be in his late 20s, handles nuclear diplomacy with the United States and delicate relations with South Korea. His consolidation of power, with the help of senior advisers who worked with his father and grandfather, appears to be going smoothly, although determining the intentions and internal dynamics in Pyongyang is notoriously difficult. North Korea faces tough U.N. sanctions that were tightened in 2009 when it conducted its second nuclear test and launched a long-range rocket. In late 2010, Pyongyang unveiled a uranium enrichment facility that could give North Korea a second route to manufacture nuclear weapons in addition to a plutonium-based program. Willard said the North is developing, but has not yet tested, a road-mobile, intercontinental ballistic missile system that could be more difficult to observe than its other ballistic missiles. In the meantime, millions continue to go hungry, according to the World Food Program. The North, which has little arable land, suffered a famine in the 1990s that killed hundreds of thousands of people, and chronic food shortages persist. U.S. charities reported after a trip to North Korea late last year that scores of children were suffering "slow starvation." The United States said officials will meet soon to finalize details for a proposed package offering an initial 240,000 metric tons of food aid for hungry children. Washington has promised intensive monitoring of the aid, a reflection of U.S. worries that food could be diverted to the North's powerful military. Nuland said U.S. officials would seek to do so by consultations with the North Korean mission at the United Nations in New York. She said if necessary the two sides could hold a meeting in Beijing but nothing has been scheduled.