"(McMaster) said he is aware of the procedural problem in South Korea and understands it".
She indicated that if a new test looked to be long range and if it leans towards an intercontinental ballistic missile that could reach the United States, Washinton and Beijing have agreed to take action.
Japanese Prime Minister Shinzo Abe said Thursday that South Korea is the "most important" country that shares strategic interests, adding he will move toward building future-oriented ties between the Asian neighbors.
He added that this is in line with Moon's statement at a Sunday meeting of the South Korean National Security Council that dialogue is possible only if and when there is a change in North Korea's behavior.
Harris made the remarks during a speech before a think tank in Tokyo on Wednesday after meeting with Japanese leaders. It has ignored calls to rein in its nuclear and missile programs, even from China, its lone major ally.
This undated picture released by North Korea's Korean Central News Agency (KCNA) via KNS on March 7, 2017 shows the launch of four ballistic missiles by the Korean People's Army (KPA) during a military drill at an undisclosed location in North Korea.
"Should North Korea conduct additional nuclear tests, then Japan would seek additional sanctions through fresh UN Security Council resolutions", he said.
The two Koreas - technically still at war after the 1950-53 conflict ended only with a ceasefire - have occasionally clashed along the border.
He especially underlined the United States' commitment to defend Japan in the event of a crisis saying that no one should doubt the US resolve to meet its treaty obligations to Japan.
Moon, who has been an advocate of engagement with the North, said during his campaign last December that Pyongyang would be the first destination he would visit if elected president.
It is too premature, he said, to have any US-North Korea talks.
Han said the THAAD anti-missile unit deployed by the United States military in the South detected the missile, marking the first time the controversial system has been put to use since its deployment in April.
US President Donald Trump said on May 17 he is willing to engage North Korea but emphasized "right conditions" as a prerequisite, Seoul's special envoy said.
China has strongly opposed THAAD. South Korean businesses have faced boycotts, especially the retail group Lotte which provided the land on which the system is being constructed.
The U.S. admiral called North Korea, which test fired a new intermediate-range ballistic missile (IRBM) on May 14, "a clear and unsafe threat" to the United States, Japan and to South Korea. She also added that any country that doesn't implement the United Nations sanctions is supporting Pyongyang's actions.
Ahead of a closed-door U.N. Security Council meeting, Nikki Haley, the U.S. Ambassador to the United Nations made it very clear that Washington would only talk to North Korea once it halted its nuclear program.
"It is actually North Korea trying to intimidate the worldwide community", Haley said, "and Russian Federation itself should be concerned because that ballistic missile test was a signal to South Korea for their new elections, it was a signal to Russian Federation in how close it got, it was a signal to Japan being in the region, and it was a signal to us".
Trump has said "a major, major conflict" with North Korea was possible and all options were on the table but wanted to resolve the crisis diplomatically and peacefully, possibly through the use of economic sanctions.