Calling North Korea a "disgrace," Republican presidential front-runner Donald Trump said Sunday that China should solve the problem as Pyongyang's main benefactor or be forced to see its trade with the United States suffer.

It was the latest in a series of remarks that Trump has been making since the North's nuclear test last week to underscore his point that China has "total control" over Pyongyang, and the U.S. should force Beijing to fix the problem of the North.

"I think North Korea is a disgrace," he said on "Fox News Sunday." "I would get China, and I would say, 'Get in there and straighten it out. You'd better straighten it out.' And, if you don't straighten it out, we're going to have trouble because we have power over China. We have trade power over China."

Trump also said that while Iran is expected to have nuclear weapons due to what he calls a "stupid agreement" that the U.S. and other world powers concluded with Tehran last year, North Korea already has "very dangerous weapons of some sort."

In another FOX TV interview, Trump again said that China is the one that should fix the North Korea problem.

"People ask me a number of questions. They were asking me how do you solve North Korea? Well, China should be solving North Korea; they have total power," Trump said. 

"I say we can beat them so badly; we have such power over China with trade because we have rebuilt China. They have taken so much out of our economy in terms of money that we can -- we have a lot power over China. They should solve the North Korea problem," he said.

Last week, Trump said that the U.S. should be very tough with China on trade unless it cooperates in reining in the North, even claiming that the U.S. can have China collapse "in about two minutes."

Trump again repeated his unfounded criticism that South Korea is getting a defense free ride from the U.S. while paying only "peanuts" for the upkeep of the 28,500 American troops stationed in the country to help defend against the North.

"I order thousands, and thousands of televisions a year. They're all made in South Korea, whether it's Samsung, LG; they're made in South Korea. Every time I order, South Korea gets huge checks, right?" Trump said.

"They're a monster. They are absolutely a behemoth in terms of economics. An economic behemoth. Now, we're sitting there with 28,000 soldiers on our line between North Korea and South Korea. We get paid almost nothing. We get paid peanuts. We're not being paid," he said.

The presence of U.S. troops in South Korea is a legacy of the 1950-53 Korean War, which ended in a truce, not a peace treaty, leaving the divided peninsula still technically at war, and Seoul has long shared the cost of stationing U.S. forces. 

In 2014, the two countries renewed their cost-sharing agreement, known as the Special Measures Agreement, with Seoul agreeing to pay 920 billion won for the upkeep of the U.S. troops in 2014, a 5.8 percent increase from a year earlier.

Moreover, the American military presence on the peninsula is seen as in line with U.S. national interests in a region marked by a rising China. (Yonhap)