America is drawing up plans for a “bloody nose” military attack on North Korea to stop its nuclear weapons programme, The Telegraph understands.

The White House has “dramatically” stepped up preparation for a military solution in recent months amid fears diplomacy is not working, well-placed sources said.

One option is destroying a launch site before it is used by the regime for a new missile test. Stockpiles of weapons could also be targeted.

The hope is that military force would show Kim Jong-un that America is “serious” about stopping further nuclear development and trigger negotiations.

Three sources - two former US officials familiar with current thinking and a third figure in the administration - confirmed military options were being worked up.

“The Pentagon is trying to find options that would allow them to punch the North Koreans in the nose, get their attention and show that we’re serious", said one former US security official briefed on policy.

Donald Trump, the US president, has vowed to end the North Korean's nuclear weapons programme credit: SAUL LOEB/AFP/Getty Images

Donald Trump’s decision to bomb a Syrian government airfield earlier this year to defend America’s “red line” on chemical weapons use is seen as a blueprint.

Details have emerged after this newspaper talked to around a dozen current and former officials in America and Britain about policy towards North Korea.

The conversations show that the Trump administration is more willing to consider military options to end the conflict than widely assumed.

It can be revealed that senior British diplomats fear America has already begun a “step by step” military build-up in the region that could escalate.

Alastair Morgan, the UK ambassador to North Korea, visited Washington DC for behind-closed-doors talks about forcing the regime to the negotiating table last month.

The UK is also urging Southeast Asian and African countries to expel some North Korean diplomats amid fears they are secretly financing the regime.

Meanwhile America wants North Korean ships to be stopped and searched amid fears they are being used to get round UN sanctions.

Pressure to act comes from the drop in estimated time it will take for North Korea to develop a missile that could hit America with nuclear weapons.

Kim Jong-un overseeing weapons development at an undisclosed location in North Korea credit: Korean Central News Agency/Korea News Service via AP, File

Just a few years ago it was believed the regime was a decade away from that point, but now the figure has dropped to as little as 18 months - though estimates vary.

Senior figures in the Trump administration have made clear in public that it would be unacceptable for North Korea to reach that position.

View more!

While Mr Trump has always said a “military option” is on the table, the administration's focus has been on building economic and diplomatic pressure.

But Mr Kim’s refusal to negotiate has left senior White House figures disillusioned with diplomacy and increasingly considering military avenues.

One British source who recently attended a briefing with H.R. McMaster, Mr Trump’s national security adviser, and other officials left feeling alarmed.

“The Americans said deterrence doesn’t work against North Korea and negotiation doesn’t work,” the source said.

“Those who heard them left with the impression that military action is very much an option they were considering seriously.”

Kori Schake, a former director of defense strategy at the White House’s National Security Council who served under George W Bush, said military action is a real possibility.

"The White House very strongly believes that either North Korea will agree to give up its nuclear weapons or we will launch a preventative attack to destroy them,” she said.

"I would put the odds of them actually carrying that out at three in 10. Other policy experts say it is four in ten."

British officials are continuing to urge their US counterparts to focus on diplomatic solutions and are looking to increase pressure on North Korea.

View more!

Alongside European Union allies the UK is urging Southeast Asian and African countries who have lots of the regime’s diplomats to check their activities.

There are concerns that some North Korean officials based abroad use nefarious means to generate money to send home, thereby funding the regime.

Mr Morgan, one of the few foreign diplomats to be stationed in North Korea, visited Washington DC for three days at the end of November for talks.

He met officials from the White House, State Department and Treasury as well as congressmen to discussing how to maximise pressure on the regime.

Donald Trump steps off Air Force One in Maryland on December 2 credit: MANDEL NGAN/AFP/Getty Image

While the Trump administration is considering military options, it is not a foregone conclusion that the US president will choose to go down that path.

There are major uncertainties about how Mr Kim would react if provoked and the regime already has missiles that could strike nearby countries including Japan and South Korea.

Experts also say there is a split in the US administration with Mr Trump and Mr McMaster more willing to consider military action than Rex Tillerson, the secretary of state, and Jim Mattis, the defence secretary.

The White House, State Department and Pentagon declined to comment.