He said: "The President has been very clear, militarily, we are going to be prepared should something go wrong and our military is prepared".
Last month, North Korea said it had successfully tested a new type of ICBM that could reach all of the US mainland and South Korea and USA -based experts said data from the November 29 test appeared to support that.
North Korea's latest missile test, which USA experts say indicated an increasing technological sophistication, did not demonstrate an imminent threat of nuclear attack on the United States, Defense Secretary Jim Mattis said Friday.
Speaking in a press conference at the United Nations, Mr Tillerson said the U.S. would not "accept any preconditions" for talks with North Korea.
Boris Johnson told fellow Tory MPs that North Korea's rockets would be capable of hitting London by next June.
US -based experts, some of whom have been skeptical about past North Korean claims, said last month that data and photos from the test appeared to confirm North Korea had a missile of sufficient power to deliver a nuclear warhead anywhere in America.
China's deputy United Nations ambassador is pushing back against USA insistence that the Asian country holds the key to resolving North Korea's escalating nuclear and ballistic missile programs.
He told reporters after the meeting that the United States would not accept any preconditions for talks with North Korea.
Google launches a AI Center in China
Google's search engine is banned in the Chinese market along with its app store, email and cloud storage services. The field is now one of the most competitive in technology, driven by demand for skilled experts.
U.S. Secretary of State Rex Tillerson (front) addresses a United Nations Security Council meeting on the situation on the Korean Peninsula at the UN headquarters in NY, on December 15, 2017.
He also criticized unilateral sanctions against North Korea which the U.S., European Union, Japan and others have imposed saying they undermine Security Council unity "and should be abandoned". State Department spokesperson Heather Nauert walked back his statement the next day, however, saying that North Korea would have to suspend its weapons tests before such talks could take place.
The Security Council has ratcheted up sanctions on North Korea over its weapons programs since 2006.
"The hope for peace is not totally obliterated", said Chinese Deputy Ambassador Wu Haitao.
Pyongyang has carried out its sixth nuclear test and conducted a series of missile launches including its first tests of two intercontinental ballistic missiles (ICBM) this year.
While Feltman received no firm commitment on talks from North Korea, he said the visit was "just the beginning" of his push for "talks about talks".
Instead of responding, the ambassador said the council has adopted 11 sanctions resolutions against North Korea.
He urged the Security Council not to backtrack from the demand that North Korea abandon its nuclear and missile programs "in a complete, verifiable and irreversible manner".