In addressing the Trump administration’s biggest national security challenge, the U.S. Treasury sanctioned one person, 27 companies and 28 ships, according to a statement on the U.S. Treasury Department’s website.

The Treasury’s Office of Foreign Assets Control announced the measures, which are designed to disrupt North Korean shipping and trading companies and vessels and to further isolate Pyongyang.

The ships are located, registered or flagged in North Korea, China, Singapore, Taiwan, Hong Kong, Marshall Islands, Tanzania, Panama and Comoros.

Washington “also issued an advisory alerting the public to the significant sanctions risks to those continuing to enable shipments of goods to and from North Korea.”

“Today I am announcing that we are launching the largest-ever set of new sanctions on the North Korean regime,” Trump said in excerpts of a speech he was to deliver on Friday to a conservative activist group.

North Korea’s missile and nuclear program is seeking to develop a nuclear-tipped missile capable of reaching the U.S. mainland. Trump and North Korean leader Kim Jong Un have taunted each other through the media and in August Trump threatened to go beyond sanctions by bringing “fire and fury like the world has never seen.”