WASHINGTON -- US President Donald Trump's "disruptive" approach to North Korea could prove to be good for resolving the problem that has defied conventional solutions for decades, former Defense Secretary Robert Gates said.

"The disruptive nature, the tough talk on North Korea, the military deployments, sending the missile defense system to South Korea, I think these are all good things to have done. And I think he's gotten China's attention to a degree that his predecessors have not, that this is a very serious matter for the United States," Gates said on CBS "Face the Nation."

Gates, who served as defense secretary from 2006 to 2011 under President George W. Bush and his successor, Barack Obama, also said that the past three US administrations followed "a pretty consistent policy toward North Korea and it really hasn't gotten us anywhere."

"So the notion of disrupting and sort of putting the Chinese on notice that it's no longer business as usual for the United States I think is a good thing," he said.

Recalling his last visit to China as secretary in 2011, Gates said that he told Chinese President Xi Jinping that the US considers the North a direct threat to the U.S, but the appeal had "no effect whatsoever" on the Chinese.

Thanks to the disruptive approach, however, Trump has "their attention," he said.

Gates cautioned that Trump shouldn't overestimate the influence China has with the North.

"It's clear the relationship between China and North Korea has hardly ever been worse. Kim Jong-un has never been to Beijing in his leadership. President Xi has never been to North Korea. That's a first in that relationship," Gates said.

"The Chinese press are saying some amazingly negative things about the North, and about Kim Jong-un. So they are weighing in, and they are bringing greater pressure. Whether it will be enough, I think, remains to be seen," he said. (Yonhap)