WASHINGTON — The Trump administration unfurled new sanctions on Wednesday targeting North Korea and its weapons program, underscoring the aggressive approach that President Trump has promised to take against the government of Kim Jong-un.

The new sanctions, released by the Treasury Department, target North Korean and Chinese trading companies, North Korean ships and North Korea’s ministry of oil. They also hit North Korean representatives in China and Russia who are members of the Workers’ Party of Korea and who have helped North Korea transfer chemicals and equipment used for weapons production.

“Treasury continues to systematically target individuals and entities financing the Kim regime and its weapons programs, including officials complicit in North Korean sanctions evasion schemes,” Steven Mnuchin, the Treasury secretary, said in a statement.

Mr. Mnuchin said that, in accord with United Nations Security Council resolutions, he also is calling on Russia and China to expel anyone working in their countries on behalf of North Korea’s financial networks.