US President Barack Obama signed an order Wednesday implementing UN-backed sanctions on North Korea after a nuclear test and missile launch this year, as Pyongyang promised reprisals.

US President Barack Obama signed an order Wednesday implementing UN-backed sanctions on North Korea after a nuclear test and missile launch this year, as Pyongyang promised reprisals.

The White House said Obama had signed an executive order targeting the volatile hermit state's energy, financial and shipping assets.

The measures were agreed to at the United Nations in response to the January 6 nuclear test and February 7 ballistic missile launch.

"The order is not targeted at the people of North Korea, but rather is aimed at the government," said the document signed by Obama.

Among the entities targeted are the "Propaganda and Agitation Department" of the Workers' Party of Korea and mining firms that provide the regime with much-needed revenues.

In response to the UN sanctions and a US-South Korean drill, Kim has already ordered an upcoming nuclear warhead test and multiple ballistic missile launches.