Trump announces 'heaviest ever' sanctions on North Korea

US President Donald Trump rolled out sanctions against North Korea-linked shipping assets on Friday, hailing the package as the "heaviest sanctions ever" levied on the Pyongyang regime.

Trump used his address at the Conservative Political Action Conference just outside Washington to step up his campaign of "maximum pressure" designed to force North Korea to roll back its weapons programmes.

"We imposed today the heaviest sanctions ever imposed on a country before," Trump claimed at the end of a 90-minute campaign-style address.

In light of past US embargoes, that is likely an overstatement, but Treasury Secretary Steve Mnuchin confirmed the sanctions covered "virtually all the ships" North Korea is "using at this moment in time."

Trump's administration is locked in a nuclear stand-off with North Korea, which is trying to develop missiles that could deliver a nuke to major cities in the United States.

The latest sanctions are designed to put the squeeze on North Korea's already precarious economy and fuel supply.

Mnuchin said there were signs that effort was starting to have an impact, but did not elaborate.

The North Korean military and broader economy depend heavily on imports of coal and oil from China and Russia.

China has steadfastly rebuffed Washington's calls for a full oil embargo – fearing the chaotic collapse of the Pyongyang regime – but has accepted caps agreed at the United Nations.

TRT World's Denee Savoia reports.

Arming America

Trump, defending his controversial proposal to arm some of America's teachers, said that a teacher with a gun would have "shot the hell" out of the teenager who went on a shooting rampage last week at a Florida high school.

Trump also called for stronger background checks for gun buyers and criticised an armed deputy who failed to intervene during the shooting at the Parkland, Florida, school which left 17 people dead.

Florida Governor Rick Scott announced plans, meanwhile, to station a police officer at every public school in the southern state and to increase the minimum age for gun buyers from 18 to 21.

Trump added, "well-trained" teachers could help stop school shootings.

"Maybe 10 percent or 20 percent of the population of teachers," he said. "Not all of 'em, but you would have a lot.

"And the beauty is it's concealed," Trump said.