Jack Keane, a four-star general who turned down Trump's offer of Defense Secretary, issued a stark warning on North Korea

A four-star general with close ties to Donald Trump has warned that military strikes are 'rapidly' becoming the only solution to North Korea's nuclear program.

Jack Keane, who declined the President's offer to become Defense Secretary last year, said bombing Kim Jong-un's nuclear facilities 'may be the only option left.'

His stark assessment comes ahead of a meeting between Trump and Chinese premier Xi Jinping on Thursday and Friday at Mar-a-Lago, where the subject of North Korea is expected to dominate.

Trump signaled his agenda for the talks on Monday, when he told reporters that America is willing to go it alone in order to 'solve North Korea'.

Speaking to The Times on Tuesday, Keane said: 'A preemptive strike against launch facilities, underground nuclear sites, artillery and rocket response forces and regime leadership targets may be the only option left on the table.

'We are rapidly and dangerously moving towards a military solution.'

Keane believes talks with China over more sanctions against Kim Jong-un's regime are likely to fail, leaving pre-emptive strikes as 'the only option left on the table'

Keane added that any attempt to pressure the Chinese into sanctioning North Korea is likely to end in failure.

'Our attempts to leverage China in the past have failed miserably,' he said.

'Sanctions have not worked against North Korea and I doubt more sanctions will and I don't believe sanctions against China will work any better.'

While it is not clear what exactly Trump meant by 'solving' North Korea, he was likely referring to shutting down the country's nuclear weapons program, rather than removing the Kim regime entirely.

Back in January Trump tweeted that North Korea was 'in the final stages' of developing a weapon capable of hitting the US, pledging: 'It won't happen.'

Donald Trump is due to meet Chinese premier Xi Jinping at his Mar-a-Lago resort this week where the issue of North Korea will be at the top of the agenda

Opinion on how long it will actually take the communist state to develop such a weapon varies, though most respectable sources estimate it could happen within the next four years.

Earlier this year the regime launched newly developed missiles from an airbase in the country's north which flew roughly 310 miles before dropping into the ocean, while last year it is thought to have conducted two nuclear weapon tests.

Any solution involving China is likely to rely on further economic sanctions, as the country is responsible for around 90 per cent of North Korea's trade.

Other options could include cyber attacks against North Korean nuclear facilities, such as the Stuxnet virus attack on Iran, though this would likely only delay the program, rather than end it.