"Because the actions that they're undertaking, as we've said countless times, in the past many weeks, are simply steps that further isolate them from the world," White House Press Secretary Robert Gibbs said at his daily press briefing.

"... The administration and I think, all our allies involved in the talks, believe that it's important for North Korea to take necessary steps, to live up to responsibilities and agreements that it entered into; that coming back to the table, to have productive talks, are important," Gibbs said.

Meanwhile, US Ambassador to the UN Susan Rice told reporters at the world body's headquarters in New York that "productive discussions" were on with nations to bring a "strong resolution" against the North.

"We are having very good and productive discussions. These discussions continue. I think we are making progress, and I am hopeful that in due course we will be producing a very worthy and strong resolution," Rice said.

The Deputy Secretary of State, James Steinberg said the US is working to find a common ground among nations on the steps to adopt a new resolution and on ways to follow it up.

Meanwhile the State Department said: "there is a unity of purpose among all major powers of the world on this issue here, to hold the North accountable for the bellicose actions and threats that it has made over last several weeks, months".

"We're going to continue to work that issue up in New York," Wood said.

"Just because it's taking more time, you shouldn't read it in any way as giving the North more leverage or us losing leverage. It's not really a question of leverage, it's a question of making sure that we get the strongest possible response to the North's activities," Wood said.