US President Barack Obama vowed to “lead the world” in taking action against North Korea after it defiantly exploded an atomic device on Tuesday, its most powerful nuclear test yet.

“Provocations of the sort we saw last night will only hurt them further, as we stand by our allies, strengthen our own missile defense, and lead the world in taking firm action in response to these threats,” Obama said in his State of the Union Address.

Obama also said the test would be a setback for the impoverished country, according to Reuters.

“The regime in North Korea must know that they will only achieve security and prosperity by meeting their international obligations,” he said.

Reports of the nuclear test, which Pyongyang claims was an act of self-defense against “US hostility”, quickly drew international condemnation, prompting global powers to call for even tighter measures against the pariah state, including its closest ally, China.

Beijing summoned North Korean ambassador to lodge a “stern” protest over the nuclear test and urged Pyongyang to “stop any rhetoric or acts that could worsen situations and return to the right course of dialogue and consultation as soon as possible,” Foreign Minister Yang Jiechi said.

Japanese Prime Minister Shinzo Abe said the test was a “grave threat” and said his government would respond by imposing new sanctions against the reclusive state.

Japan restricted five deputy chiefs of North Korea’s de facto embassy, the pro-Pyongyang General Association of Korean Residents in Japan, to travel to North Korea, Asahi Shimbun reports.

Abe said Tokyo would respond to the provocation in tandem with the international community following tighter UN sanctions over the North’s rocket launch in December.