John Kerry, the recently appointed US secretary of state, has urged the international community to impose more effective pressure against North Korea over its nuclear ambitions to send a strong message to Iran, which has also been sanctioned repeatedly over its uranium enrichment programme.
Kerry said on Wednesday that nations must agree on a "swift, clear, strong and credible response" to Pyongyang's third nuclear test.
"It's important for the world to have credibility with respect to our nonproliferation efforts,'' Kerry told reporters after meeting Jordanian Foreign Minister Nasser Judeh at the US State Department.
"Just as it's impermissible for North Korea to pursue this kind of reckless effort, so we have said it's impermissible with respect to Iran. What our response is with respect to this will have an impact on all other nonproliferation efforts," he said.
In defiance of UN Security Council resolutions, the latest issued last month, North Korea detonated a nuclear device at a remote underground site.
The fresh resolution warned of "significant action" if Pyongyang conducted another rocket launch or a nuclear test.
Referring to the UN statement, Kerry said: "If you are going to say things, they have to mean something. And to mean something you have to be prepared to follow up, and that's exactly what we are prepared to do."
European Union Foreign Policy Chief Catherine Ashton, speaking on Wednesday at the Security Council, called North Korea's nuclear test "a further blatant challenge to the global non-proliferation regime".
She said it was vital for the international community to stand united and demonstrate "that there are consequences of continued violations".
In Washington DC, US Defence Secretary Leon Panetta said that North Korea's actions represent a clear threat to the United States and undermines regional security.
He vowed that the US will take whatever steps necessary to meet its commitment to South Korea, including continued military exercises and increases in missile defence in the region.
Panetta said US technical experts are still assessing available data to learn more about the underground explosion.
In a speech on Tuesday, US President Barack Obama warned North Korea following its latest nuclear test, which he called a "provocation" that could lead to the US "taking firm action in response to the threat".
UN Secretary General Ban Ki-moon also condemned Pyonyang's latest nuclear test, saying he was "exploring further action" against it.
"This was an outrageous and reckless act. I have deep concerns about the impact on regional stability and the global effort to curb nuclear proliferation," he said on Wednesday.