BEIJING » Key issues on deliveries of American food aid to North Korea have been resolved, though details remain to be settled after talks ended Thursday.

Envoy Robert King called the day-and-a-half of talks with North Korean officials "positive and productive." He declined to disclose details before reporting back to Washington.

"We resolved the administrative issues we were concerned with," King told reporters at Beijing’s main airport before boarding a flight for Washington. He later said: "We’re still working on the details."

The talks follow a deal announced last week in which the U.S. offered 240,000 tons of food aid in return for North Korea freezing long-range missile and nuclear tests and for halting a uranium enrichment program that would be monitored by UN inspectors.

That agreement is the most substantive sign of warming U.S.-North Korean ties after three years of tensions during which Pyongyang exploded a nuclear device and engaged in armed provocations against South Korea.

If carried out, the agreement would bring the region closer to restarting multinational negotiations on North Korea’s nuclear disarmament. U.S. officials have cautioned that Pyongyang must take other actions before resuming the talks, chiefly improving its mostly fraught relations with Seoul.

North Korean and South Korean diplomats involved in the six-party nuclear talks are in the United States this week attending an academic conference that may help break the ice. Yet tensions remain as the U.S. and South Korea staged war games in recent days, and in apparent response, North Korea held its own drills and called for a "sacred war" against the South.

Poor and reliant economically and diplomatically on China, North Korea has been looking at ways to reform its lagging economy. The regime is also believed to be trying to lay in food and money for high-profile celebrations next month to celebrate the centenary of revolutionary founder Kim Il Sung.

In the food talks, negotiators sparred in previous rounds over North Korean demands for rice, instead of the nutritional assistance, like vitamin supplements that the U.S. agreed to provide. The U.S. also wanted to ensure that the assistance reaches North Koreans who need it, rather than being diverted to the military or other groups as was suspected with some previous international aid shipments.

King, the U.S. envoy, said in response to reporters questions said that those concerns about the shipments had been resolved, though he did not discuss how deliveries would be monitored.

North Korea’s positive outreach to Washington has surprised U.S. diplomats. Though the uptick in relations began in the middle of last year, many North Korea watchers expected the momentum to stall after North Korean dictator Kim Jong Il’s sudden death in December left power in the hands of his untested son and a coterie of advisers.

Instead, U.S. forensic teams are also expected to resume searches in North Korea next month for the remains of American military personnel missing from the 1950-53 Korean War.