US President Barack Obama has signed an order imposing UN-backed "robust new sanctions" on North Korea. The move comes amid a series of reprisals from Pyongyang, including the jailing of a 21-year-old American student.
The document signed by Obama stressed that the order was "not targeted at the people of North Korea, but rather is aimed at the government."
"These actions are consistent with our longstanding commitment to apply sustained pressure on the North Korean regime," White House spokesman Josh Earnest added in a statement.
"The US and the global community will not tolerate North Korea's illicit nuclear and ballistic missile activities, and we will continue to impose costs on North Korea until it comes into compliance with its international obligations."
Sanctions targeting North Korea's assets
The White House announced that Obama's executive order for the sanctions primarily targeted North Korea's mining, financial and shipping assets, as well as the "Propaganda and Agitation Department" of the Workers' Party of Korea.
The US Treasury Department estimates that mining alone generates more than $1 billion (890 million euros) a year for the government, providing the regime with much-needed revenue.
North Korean leader Kim Jong Un has already ordered an upcoming nuclear warhead test and multiple ballistic missile launches in response to the UN sanctions and to an ongoing US-South Korean military drill.
Conviction of US student
On Wednesday, North Korea also jailed a 21-year-old American student. Otto Warmbier was sentenced to 15 years' hard labor for stealing a propaganda banner from a hotel. North Korean state news outlet KCNA said that Warmbier had committed his offense "pursuant to the US government's hostile policy" toward North Korea.
According to KCNA, Warmbier's defense attorney had claimed that the gravity of the crime was such that he would not be able to pay even with his death but proposed to the court a sentence reduced from the prosecution's request of a life sentence.
White House spokesman Earnest called for Warmbier's release, accusing Pyongyang of using US citizens as "pawns to pursue a political agenda.
"We strongly encourage the North Korean government to pardon him and grant him special amnesty and immediate release," he said.
"The allegations for which this individual was arrested and imprisoned would not give rise to arrest or imprisonment in the United States or in just about any other country in the world."
North Korea has a long history of detaining foreigners and has used jailed Americans in the past to extract high-profile visits from the United States. In 2014, the country released three detained Americans after the personal intervention of US Secretary of State John Kerry.
The United States has no diplomatic relations with North Korea and remains technically at war with the secluded nation since the 1950-1953 Korean War ended in an armistice rather than a peace treaty.