"If it flies, it will die", Adm. Harry Harris Jr., told Congress.
North Korea conducted live-fire artillery drills and a US guided-missile submarine arrived in South Korea on Tuesday, as the Trump administration prepared an extraordinary White House briefing for senators on the escalating nuclear threat.
North Korea conducted a big live-fire exercise on Tuesday on its east coast as the nation marked the 85th anniversary of the founding of its military.
Khoon Goh, head of Asia research at ANZ, told CNBC such a reaction is expected given " massive amounts of foreign inflows" into Asia, particularly Korea and Taiwan, over the last month "as trade tensions between the US and China have eased off".
Visitors watch the North Korea side from the unification observatory in Paju, South Korea, April 25, 2017.
In other highlights of the 42-minute interview, Trump was cool to speaking again with Taiwan's president after an earlier telephone call with her angered China.
In February it banned North Korean imports of coal, which is Pyongyang's most vital export.
"It's a billion-dollar system", Trump was quoted as saying by the Reuters news agency.
"He is a good man, he is a very good man and I got to know him very well". "One of these days soon, he will succeed".
The House GOP leadership announced late Thursday that it would vote next week on new sanctions against North Korea that would target its shipping industry and those who employ North Korean slave labor overseas.
Director of National Intelligence Dan Coats and Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, will also attend.
The Trump administration has warned that all options, including a military strike, are on the table to block North Korea from developing a nuclear-tipped missile that could reach the USA mainland.
"Certainly, with the barrage of missile launches that we've seen from North Korea over the a year ago, it's very hard to make an argument that the South Koreans should not have this kind of defensive system", she said. The secretary says North Korea has to come to the table willing to talk about giving up its nuclear weapons.
North Korea routinely accuses the United States of readying for an invasion, and threatens pre-emptive strikes to stop it.
Harris said he has adequate forces to "fight tonight" against North Korea if that were to become necessary.
North Korea has vowed to respond to any "slight provocation" from the nation's proclaimed enemies with "5 million nuclear bombs" carried by its youth. But he declined to provide specifics in an open setting.
He said it was his decision "to pull the Carl Vinson out of Singapore, truncate the exercise it was going to do south of Singapore, cancel its port visit to Australia and then proceed north".
At the same time, one of the US navy's largest submarines, the USS Michigan, which carries Tomahawk cruise missiles, docked in the South Korean port of Busan this week. It noted that the major parts of the United States missile defense system have already been installed.
A key part of the plan, it seems, is to pressure China to lean more heavily on Pyongyang to freeze its nuclear weapons programme, the BBC's Barbara Plett Usher reports. The two neighbours are concerned that the system's powerful radar can penetrate their territory and undermine their security.