The UN Security Council strongly condemned nuclear tests by North Korea and is considering "appropriate measures" in response.
The council held an emergency meeting and a presidential resolution is coming, said South Korean foreign minister Kim Sung-Hwan at UN headquarters in New York. He did not detail those "measures".
South Korea is holding the rotational presidency of the Security Council this month.
When asked if China, one of few friends of North Korea was on board, the minister said the statement he read was cleared by all members of the council.
US ambassador to UN Susan Rice said those measures could include further tightening and augmenting existing sanctions.
The US on Tuesday called North Korea's nuclear test a "highly provocative act" constituting a threat to its national security and to international peace and security.
"The danger posed by North Korea's threatening activities warrants further swift and credible action by the international community," President Barack Obama said in a statement.
The US called North Korea's pursuit of WMDs "ill-advised", and it is impoverishing its people in the process. The US also announced non-proliferation sanctions against four Chinese entities and multiple others for trading in prohibited items with North Korea, Syria and Iran. The others named included two Belarusian entities, two from Iran entities, two from Sudan, and one each from Syria and Venezuela.
Reports of a nuclear test by North Korea were a matter of deep concern, India's foreign ministry said on Tuesday. "It is a matter of deep concern that DPRK (Democratic People's Republic of Korea) has acted in violation of its international commitments in this regard," the external affairs ministry said.