The sanctioned entities include three trading companies based in Dandong, northeastern China, which are accused of exporting some $650 million in goods to the North and importing another $100 million between January 2013 and August 2017.

A fourth Dandong-based company, Dandong Dongyuan Industrial, allegedly exported more than $28 million in goods to North Korea over several years and worked with front companies for North Korean organizations related to weapons of mass destruction, according to the Treasury. Dongyuan's owner, Sun Sidong, was also blacklisted.

Mnuchin said the US is sanctioning shipping and transportation companies, as well as their vessels, for "(facilitating) North Korea's trade and its deceptive maneuvers."

The statement pointed out that North Korea is banned under a UN Security Council resolution from using "deceptive" shipping practices, such as ship-to-ship transfers.

One North Korean company was designated for its alleged role in exporting North Korean labor to generate income for the regime.

Two government entities -- the Maritime Administration Bureau and the Ministry of Land and Marine Transport -- were also included on the list.

Trump said a day earlier that North Korea will be under "the highest level" of sanctions once they are all announced over a two-week period.

Secretary of State Rex Tillerson also told reporters the increasing sanctions are starting to have an effect on the impoverished nation, with long lines forming at gas stations.

The UN Security Council unanimously approved new sanctions in the wake of North Korea's long-range missile tests in July and sixth nuclear test in September, to include caps on its imports of petroleum and related products.

While critics express skepticism that any amount of sanctions will force Pyongyang to denuclearize, many officials and experts agree that such economic pressure is the only solution to the standoff short of war.

"As of about a month and a half ago ... it was at least 20 countries around the world that had done different things with that maximum pressure campaign," Heather Nauert, the State Department's spokeswoman, said at a press briefing Tuesday.

"That would exclude countries being involved in UN Security Council resolutions and various sanctions," she noted, "but just countries that we've had conversations with alone, where we have said, 'Reduce the number of North Korean guest workers in your country, reduce the footprint of their embassy, kick out North Korean guest workers.'"

South Korea's foreign ministry said that it saw the latest US move as a "reaffirmation" of Washington's commitment to working together with the international community to induce the denuclearization of North Korea by using strong sanctions and pressure.

The ministry also said that South Korea and the US will maintain close cooperation and coordination at every possible level to achieve their joint objective of "peacefully" resolving the North's nuclear problem. (Yonhap)