The United States and China share responsibility for resolving the issue of North Korea's proliferation activities, U.S. Secretary of Defense Leon Panetta said.

On a trip to Asia, Panetta singled out North Korea as a continuing threat, along with the terrorism, not only in Pakistan but in Yemen and Somalia and North Africa.

"We continue to face the instability of North Korea and the potential for some kind of conflict with that country. We face the same thing with Iran," he said during a visit to the Institute for Defense Studies and Analyses in New Delhi, India, according to a transcript released Thursday by his department.

He expressed concern about proliferation by North Korea, which has conducted two nuclear tests and possesses a host of missiles.

"We also face the threat of, frankly, nuclear proliferation from an unstable North Korea -- that's something that is as much a threat to China as it is to others in this region -- and the proliferation of weapons of mass destruction," he said.

The secretary was apparently pressing Beijing to join efforts to deal with various challenges from North Korea and others, including terrorism, piracy, humanitarian and disaster needs as well as the ability to use sea lanes and protect maritime rights.

The two superpowers, dubbed G-2, have been often engaged in subtle diplomatic stand-offs over ways to deal with North Korea, China's key communist ally.

"They're threats to all of the countries in this region,"

Panetta stressed. "And it's for that reason that we all have to work together in developing a cooperative relationship and developing the capabilities of these countries so that we can all confront these issues."

He reiterated the importance of having capabilities to handle more than one enemy at a time.

"For example, if we have a war in Korea and we face a threat in the Straits of Hormuz, we have to have the ability to address both of those and to win. And we think we have projected a sufficient force to do that," he said.