President Trump on Friday announced what he called the "heaviest"-ever set of sanctions on North Korea, targeting the regime's shipping and trading companies as tensions flare anew with Pyongyang.

The president mentioned the plan during the very end of a lengthy and freewheeling address to the Conservative Political Action Conference outside Washington.

"We imposed today the heaviest sanctions ever imposed on a country before," Trump said. "Hopefully, something positive can happen."

Under the plan, the Treasury Department aims to cut off sources of revenue and fuel used to boost the country's nuclear program and military. The sanctions specifically target one individual, 27 entities, and 28 vessels.

The administration also put out an advisory warning of sanctions risks for those who enable the shipment of goods to and from North Korea.

“Treasury is aggressively targeting all illicit avenues used by North Korea to evade sanctions, including taking decisive action to block the vessels, shipping companies, and entities across the globe that work on North Korea’s behalf,” Treasury Secretary Steven Mnuchin said in a statement.

In a conference call with reporters shortly before the Trump speech, the Treasury Department’s Office of Foreign Assets Control detailed the sanctions – which are aimed at, among other things, hindering the regime's ability to transport coal and fuel in international waters. Officials said the sanctions are meant to further isolate the regime and advance a U.S.-led pressure campaign.

"We are aggressively targeting their abilities," a senior administration official said on the call.

The sanctions announcement follows Vice President Pence's trip to South Korea for the opening of the Olympic Winter Games, where he sat just seats away from Kim Jong Un's sister.

Speaking at CPAC on Thursday, Pence made clear the U.S. continues to take a firm stance against Pyongyang's nuclear program and the regime.

“I say the United States of America doesn’t stand with murderous dictatorships, we stand up to murderous dictatorships, and we will keep standing strong until North Korea stops threatening our country, our allies or until they abandon their nuclear and ballistic missiles once and for all,” Pence said.

The vice president also slammed the media for its at-times positive coverage of the North Korean dictator's sister, Kim Yo Jong.

“For all the media fawning over the sister of the North Korean dictator, I think it’s important that every American knows who this person is and what she’s done,” Pence said Thursday. “The sister of Kim Jong Un is a central pillar of the most tyrannical and oppressive regime on the planet, an evil family clique that brutalizes, subjugates, starves and imprisons its 25 million people.”

Meanwhile, Ivanka Trump and the U.S. delegation arrived in South Korea on Friday to attend the closing ceremony of the Olympics.

"My daughter, Ivanka, just arrived in South Korea. We cannot have a better, or smarter, person representing our country," President Trump tweeted on Friday.

Fox News’ John Roberts and Megan Woods contributed to this report.