Updated April 12, 2017 16:16:42

North Korea could be capable of launching a nuclear missile attack on the US within four years, according to a former top US presidential adviser.

Dennis Wilder, the former special assistant to George W Bush, warned that the world should not underestimate Kim Jong-Un or Donald Trump, amid escalating tensions on the Korean peninsula.

The US President has diverted a Navy strike group to the Korean peninsula and is urging China to do more to reign in the North, following the kingdom's threats to launch a nuclear attack on America.

Mr Wilder, a former CIA deputy assistant director for East Asia and the Pacific, told Lateline that North Korea could have a long-range intercontinental ballistic missile capable of reaching the US west coast within four years.

"Such a move would be disastrous, after all a 10-kiloton weapon could kill 100,000 people," he said.

"We believe, and American intelligence estimates say this, that the North Koreans could have such a weapon within the next four years. In other words, during the term of President Trump."

If not a nuke, artillery barrage could hit Seoul

But he said the immediate danger was for people in South Korea and other parts of the region.

"We are very aware of the dangers to the South Korean people. After all, Kim has 10,000 artillery pieces along that border," he said.

"Seoul is within artillery range of the demilitarised zone. We know that this is a dangerous situation for the South Korean people and the 10 million people there."

Trump's unpredictable — but that could be good

Mr Wilder said Mr Trump had been clear with China that the time of patience with North Korea was over.

"I do think that actually Donald Trump's unpredictability is an asset in this situation," he said.

"The Chinese can no longer be assured that the United States won't take military action. So they need to have some real hard meetings in Beijing deciding where they're going to be."

Would the US try to assassinate Kim Jong-un? Probably not

Saturday is the 105th anniversary of the birth of Kim Il-sung, North Korea's founding father and grandfather of the current ruler.

North Korea often marks such anniversaries with displays of military strength and Mr Wilder warned Kim Jong-un could not be trusted.

"We also have to be worried about him," he said.

North Korea's launch of four ballistic missiles towards Japan has unnerved the US, and it has decided enough is enough, writes Philip Williams.

"After all, what he did in Kuala Lumpur recently with the VX attack on his brother, the sinking of the naval ship with the South Koreans a few years ago, the killing of 300 people of his leadership, all of these things say to us that this is a leader you can't trust."

But Mr Wilder gave little credence to reports that the US was coordinating an assassination attempt on Mr Kim.

He said America was more likely to apply pressure to North Korea's elite.

"I think that the United States is saying to the North Korean elite, 'Look where this man has gotten you,'" he said.

"Look at the condition of North Korea in the past five years. It has the 125th smallest economy in the world. Whereas South Korea is like Australia, in the top 15 economically. The people of North Korea are deprived.

"What we are trying to do is put pressure on the North Korean elite to turn against his policies.

"Not necessarily to turn against him, not necessarily to take him out of power, but the North Korean elite, if we put pressure on them, I believe, will decide that he has taken them among the wrong road, they got very little out of this nuclear development program."

Topics: unrest-conflict-and-war, world-politics, korea-democratic-people-s-republic-of, korea-republic-of, united-states

First posted April 12, 2017 12:15:31