A senior U.S. diplomat says Washington is open to diplomacy with North Korea over its disputed nuclear program, but that Pyongyang must first follow through on its previous nuclear commitments and improve relations with South Korea.

“We agreed that a path is open to North Korea towards the resumption of talks and improved relations with the United States and the Republic of Korea through dialogue. We also underscored again, very clearly, that the road to these improved relations runs through Seoul for North Korea.”

Assistant Secretary of State Kurt Campbell made his comments Wednesday after holding talks in Seoul with South Korea's nuclear envoy Lim Sung-Nam.

Campbell said the U.S. is waiting to see whether North Korea's new leader Kim Jong Un is prepared to take the “necessary steps” before long-stalled six-nation nuclear disarmament talks can resume.

The U.S. and South Korea have insisted Pyongyang abandon its uranium enrichment plant as a precondition to the talks.

South Korean Prime Minister Kim Hwang-sik said Wednesday the six-party talks could resume if North Korea “shows sincerity.”

Since the unexpected death of former leader Kim Jong Il in December, his son and successor Kim Jong Un has given no sign that he will make concessions to improve relations with the rest of the world.

But Pyongyang has in recent weeks hinted that it is open to suspending its uranium enrichment program if it can get desperately needed food aid from the United States.

However, some of that food aid appears to now be coming from China – North Korea's biggest ally. Recent reports indicate Beijing has pledged to give North Korea 500,000 tons of food aid and 250,000 tons of crude oil, as a show of support to Kim Jong Un.

When asked about the Chinese aid, Campbell said he believes China has “taken steps to underscore their commitment to the transition in power in North Korea.” But he called on Beijing to be more transparent in sharing its goals for North Korea.

“Frankly, it's an evolving situation, we're watching it closely, and we want to continue a close dialogue with China. We want them to share with us more of their perspectives and their plans.”

North Korea has suffered from chronic food shortages since a famine in the 1990s that is believed to have killed hundreds of thousands of people. The United Nations and other international relief agencies say North Korea needs help feeding millions of its people.