The comments came hours after the South, which hosts 28,500 USA troops, said it wanted to reopen a channel of dialogue with North Korea as Moon seeks a two-track policy, involving sanctions and dialogue, to try to rein in its neighbour.
Moon's envoy to the US, South Korean media mogul Hong Seok-hyun, left for Washington early on Wednesday.
But the United States will not have any dialogue with the North for the sake of dialogue and the use of pressure was the premise in the approach to Pyongyang, Hong quoted Trump as saying, according to Yonhap.
Haley's comments at the United Nations, alongside ambassadors from Japan and South Korea, came days after North Korea tested another ballistic missile.More news: Inside the USA effort to keep laptop bomb intel secret
Nonetheless, North Korea is pressing ahead with its nuclear and missile-development program, holding another ballistic missile test on Sunday - one that experts said could be a new type of missile.
It has been working to develop a nuclear-tipped missile capable of striking the USA mainland, and experts say Sunday's test was another step toward that aim.
Wang and former South Korean Prime Minister Lee Hae-chan were expected to discuss ways of containing North Korea's missile and nuclear weapons activities as well as the economic fallout over the deployment in South Korea of the US missile defence system called THAAD.
A telephone line to North Korea at the truce village of Panmunjom may be reopened, more than a year after it was shut down after the closing of a jointly operated factory park.
The envoy replied that such remarks were a part of a process of resolving the North Korean nuclear issue. A separate summit could also be held the following month, Lee said.More news: New French Prime Minister Described himself as a Man of the Right
During a phone call with Chinese President Xi Jinping last week, South Korea's new president, Moon Jae-in, said he was aware of Chinese worries about THAAD and asked Xi to help resolve difficulties facing South Korean businesses operating in China.
In what both governments hoped was a major step forward, the two countries had agreed in 2015 to a deal created to end a row over Korean "comfort women" forced into sex slavery for Japanese soldiers during the World War II.
Abe also struck a conciliatory note, saying: "With the new president, I wish to build future-oriented Japan-South Korea relations".
Moon has sent envoys to the United States, China, Japan and the European Union this week in what the government calls "pre-emptive diplomacy".More news: Toyota, 3 other automakers settle suit over Takata air bags
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