Washington's top priority on Pyongyang's denuclearization remains unchanged, U.S. Ambassador to South Korea Mark Lippert reiterated Friday, dismissing the lingering speculation over potential policy differences between the allies.

In a meeting with local reporters, the ambassador made the remarks, echoing a recent series of statements by senior U.S. officials including chief nuclear envoy Sung Kim that Washington prioritizes denuclearization rather than a peace treaty with Pyongyang.

"I wouldn't add anything to what he (Kim) said other than to reemphasize our policy remains unchanged," Lippert said.

After the U.S. said earlier this month that it did not rule out the possibility of peace treaty talks, speculation persisted that it could be leaning toward China's "dual-track" approach whereby negotiations on denuclearization and a peace treaty would proceed simultaneously.

Pyongyang has persistently called for a peace treaty to formally end the 1950-53 Korean War. But Seoul dismissed it, saying talks for a peace treaty would divert attention away from denuclearization.

Lippert said in the meantime, the focus should be on the rigorous implementation of a new U.N. Security Council (UNSC) sanctions resolution, which he called "strong, robust and unprecedented." Earlier this month, the UNSC adopted the resolution to punish Pyongyang for its nuclear test in January and long-range rocket test in February.

"The focus is on strong implementation of the sanctions and making sure the sanctions are as effective as possible to drive the North Koreans back to the negotiating table," the ambassador said.

He pointed out the sanctions are designed to "sharpen" Pyongyang's choice, curb the growth of its nuclear and missile programs and offer a return to negotiations at the long-stalled denuclearization talks involving the two Koreas, the U.S., China, Japan and Russia.

"I think there is no argument that these unprecedented sanctions certainly do accomplish the objective of sharpening the choices, imposing costs and adding significant downsides to continuing on a course of nuclear weapons development and missile development," he said.

Responding to a question about whether a series of fresh sanctions against the North are intended ultimately to cause a regime change, Lippert said Washington's goal is to fundamentally solve the denuclearization issue through "principled diplomacy" -- as witnessed in the case of Iran.

"Our policy is not a regime change," he said. "Sanctions aren't an end to themselves. They are the means to it."

Touching on China's opposition to the potential deployment of a Terminal High-Altitude Area Defense (THAAD) missile interception system to Korea, the ambassador said THAAD is not a "bargaining chip."

Stressing that any decision over THAAD here will be based on "national security interests," he also dismissed the speculation that there was a political deal between Washington and Beijing over THAAD to adopt the latest package of UNSC sanctions on Pyongyang.

The allies have launched official talks to discuss the feasibility of deploying THAAD to Korea. They have highlighted the defensive nature of THAAD. But Beijing and Moscow have vehemently opposed it, claiming it -- particularly its long-range radar system -- could target them. (Yonhap)