The U.S. will not allow the resumption of the long-stalled six-party talks on ending North Korea's nuclear program until the communist country takes "meaningful" steps to denuclearize, a visiting U.S. senator said Monday.

The six-way talks, involving the two Koreas, the U.S., China, Russia and Japan, have been stalled since late 2008. The North has recently expressed its willingness to reopen the disarmament-for-assistance talks, and has rallied political backing from Russia and China.

Arizona Senator John McCain, however, echoed U.S. president Barack Obama when he demanded that the North first take substantial actions toward denuclearization before the U.S. allows the resumption of the talks.

"There should be no reward for empty rhetoric from North Korea," McCain said in a press conference in Seoul. "Until the North Korean regime shows meaningful steps toward denuclearization, there should be no relaxation of pressure, no resumption of six-party negotiations."

The senator added that the U.S. remains committed to the security of the Korean Peninsula, and called the U.S.-South Korea alliance "unshakable."

McCain and Sheldon Whitehouse, a Rhode Island senator, have been in South Korea since Sunday to discuss North Korean humanitarian issues with South Korean experts, as well as with President Park Geun-hye.

The senator also said the North is now falling short of the U.S. conditions for forging a permanent peace treaty that will replace the currently-effective Armistice Agreement that ended the 1950-53 Korean War.

The North has repeatedly demanded a peace treaty be signed between the countries.

"I cannot imagine North Koreans allowing free and fair elections with international observers. And it seems to be that will have to be the basis of a peace treaty," the senator said, adding that he is skeptical the North "would respect the will of the people."

The North should also show "some accommodation in human rights if they want a lasting treaty," he said.

Meanwhile, McCain urged South Korea and Japan to start negotiations in order to resolve their current disputes over historical issues.

The Abe government in Japan has reiterated claims to Dokdo, South Korea's easternmost islets, and made nationalistic remarks aimed at whitewashing its wartime atrocities, much to the chagrin of South Korea and other victim nations of Japan's past colonial rule.

"Sometimes we have to resolve issues and move forward," the senator said. “What happened in the past, however terrible and tragic, should not be the reason why there should be no progress in the relations in the countries," he said, adding that "I don't think it is the right approach."

The trilateral collaboration among the neighbors and the U.S. is crucial when the region is facing the young North Korean leader Kim Jong-un and a newly assertive China, he said. (Yonhap News)