Without getting into the specifics of what it may or may not do, the United States has issued a blunt warning to North Korea that it can either have a future or nuclear weapons.

"It cannot have both," US Assistant Secretary of State Christopher Hill said capping a day of high drama played out in world capitals, at the United Nations and in Washington.

The senior administration official did not specify as to what steps the United States will take but stressed that Washington will do all it can to dissuade North Korea from the nuclear test it has threatened.

"We are not going to live with a nuclear North Korea, we are not going to accept it," Hill told the US-Korea Institute by way of a response to North Korea's announcement that it will conduct its first nuclear test.

"We would have no choice but to act resolutely to make sure that North Korea understood -- and to make sure that any other country understands -- that this (test) is a very bad mistake," Hill said, making the point that this was indeed a 'very tense time' in dealing with Pyongyang.

"We passed a message of our deep concern about this test. We did not receive any answer of course. They just took the message."

At the State Department, Deputy Spokesman Tom Casey said Washington was working at different levels to come to terms with the issue and that it was imperative to end these threats and get back to the six party talks framework.

"We are working in the Security Council. We certainly hope to see some action there in the near future. And we will be continuing to work both bilaterally and multilaterally with our partners in the region, in Europe and elsewhere to try and convince North Korea to do the right thing," Casey said in his regular briefing.

"And the right thing is to end these kind of provocations and end these kind of threats and to go back to the six-party talks, which is where we all want to be to come up with a viable solution to North Korea's nuclear programme," he said.

He also stressed that the sudden announcement coming out of Pyongyang did not impact or complicate any other pending matters like the Iranian issue.

"The issue has been something that we have been dealing with for some time and I do not see this as particularly changing or complicating any of the other dynamics that are out there with Iran or any other country," Casey said.

"A provocative action of this nature would only further isolate the North Korean regime and deny the people of the North the benefits offered to them in the Six Party Talks that they so rightly deserve," the White House has said.

US top envoy at the United Nations, John Bolton, maintained that the notion that North Korea is even threatening to conduct a nuclear test is a 'grave provocation' and as the first step, the international community has to make it clear to the reclusive regime in Pyongyang that this threat has to be withdrawn.