WASHINGTON — The Trump administration issued sanctions Friday against a North Korean business and 11 North Korean nationals who it said were tied to Pyongyang’s nuclear weapons program and the financial networks that support it.

The sanctions, brought by the Treasury Department’s Office of Foreign Assets Control, prohibit U.S. companies from dealing with the entities and also freezes any assets the entities have that are held by U.S. banks.

President Trump has said the United States should strike a tougher posture with North Korea, following years of failed efforts by the U.S. to get Pyongyang to abandon its nuclear program.

“Today’s sanctions are aimed at disrupting the networks and methods that the government of North Korea employs to fund its unlawful nuclear, ballistic missile, and proliferation programs,” Treasury Secretary Steven Mnuchin said Friday. As North Korea continues testing nuclear weapons, U.S. officials believe the isolated, totalitarian nation is working to develop technology that would allow it to put a nuclear weapon on a long-range missile that could reach the United States.

North Korea is already heavily sanctioned by the U.S. government, and it’s unclear how the new sanctions would prompt Pyongyang to change its behavior. Trump has said that neighboring China must do more to deter North Korea. That issue will likely come up when Trump meets with Chinese President Xi Jinping next week.

The new sanctions will be imposed against North Korea-based Paeksol Trading Corp., which the U.S. government accuses of exporting iron ore to China to benefit the North Korean government.

Of the 11 individuals, Treasury said they were working as agents of North Korea in Russia, China, Vietnam and Cuba.