North Korea stepped up its attack on U.S.-led sanctions, threatening to resume its nuclear program if the measures aren’t lifted.

The Foreign Ministry’s Institute for American Studies said it could revive its policy of economic construction and nuclear development if sanctions continue. The U.S. “had better stop the self-destructive act of putting pressure” on the North, the Korean Central News Agency cited director Kwon Jong Gun as saying.

The measures hamper South Korea from pursuing cooperation projects with the North, according to the institute in a statement late Friday. That echoes North Korean leader Kim Jong Un’s recent comments, saying that “vicious” sanctions stand in the way of promoting the country’s development and lead instead “to change and submission.”

The remarks come a week before a planned meeting between U.S. Secretary of State Michael Pompeo and North Korean official Kim Yong Chol to discuss details of a potential second summit between Kim and President Donald Trump. Pompeo and Kim will likely be accompanied by special envoy Stephen Biegun and North Korea’s Choe Son Hui, South Korea’s Hankyoreh reported.

Hours after the statement was released, satellite imagery seen by 38 North suggested that North Korea is continuing uranium mining and milling operations at one of the country’s largest declared uranium ore concentrate facilities.