Trump: China has 'total control' over North Korea

Republican presidential candidate Donald TrumpDonald John TrumpSean Spicer to speak at gas industry conference Ex-World Bank president: Congress must crack down on Trump’s trade policies Hillary Clinton to sit down with CBS's Jane Pauley on Sunday MORE on Wednesday said China should rein in its ally North Korea after Pyongyang said it successfully tested a hydrogen device.

"Nobody is discussing it with China. China has total control. Believe me — they say they don't — they have total control over North Korea, and China should solve that problem," Trump said in a phone interview on "Fox and Friends."

"And if they don't solve the problem we should make trade very difficult for China," he added.

Trump also slammed North Korean leader Kim Jong Un as a "madman."

Global leaders are considering their response to the isolated nation after it said that it had carried out a hydrogen bomb test, which would mark its fourth nuclear test since 2006.

Trump's GOP rivals Sen. Marco Rubio (Fla.) and New Jersey Gov. Chris Christie chided the Obama administration's "weakness" in responding to North Korea's nuclear efforts.

Another Republican candidate, Sen. Rand Paul (Ky.), floated placing stricter sanctions on North Korea and calling on China to help de-escelate the situation during an interview on CNN.