The U.S. State Department says two days of talks in Geneva between senior U.S. and North Korean diplomats on resuming six-party nuclear negotiations narrowed their differences, but there were no breakthroughs.

U.S. officials also said that although they are cautiously optimistic about the results of the meetings, it could take months to find out if Pyongyang is willing to take real steps and commitments on its nuclear obligations.

U.S. special envoy for North Korea Stephen Bosworth said he is confident the two sides eventually can reach a deal, describing the tone “positive and generally constructive.”

His North Korean counterpart, Vice Foreign Minister Kim Kye Gwan, cited “big improvements” in some areas and remaining differences that will be resolved during future meetings.

State Department spokeswoman Victoria Nuland said the Geneva meetings included North Korea's request for international food aid to cope with shortages attributed to floods and mismanagement.

Nuland said that Washington's new aid will depend on a U.S. needs assessment and competing demand for famine relief elsewhere, including the Horn of Africa. She said the U.S. also wants assurances that aid reaches North Koreans who are truly in need.

The six-party talks are aimed at getting North Korea to end its nuclear weapons program in return for diplomatic and economic concessions. They involve the United States, North and South Korea, Russia, Japan and China.

North Korea pulled out of the talks in 2009, and both Washington and Seoul are concerned about recent disclosures that Pyongyang has a sophisticated uranium enrichment program.