America is drawing up plans for a "bloody nose" military attack on North Korea to stop its nuclear weapons programme, the Daily Telegraph is reporting.
The White House has "dramatically" stepped up preparation for a military solution in recent months amid fears diplomacy is not working, well-placed sources told the newspaper.
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.
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.
President Donald Trump's decision to bomb a Syrian government airfield this year to defend America's "red line" on chemical weapons is seen as a blueprint.
The Daily Telegraph talked to about 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. Senior British diplomats fear America has already begun a "step by step" military build-up in the region that could escalate.
Trump has always said a "military option" is on the table, but the Administration's focus has been on building economic and diplomatic pressure. But Kim's refusal to negotiate has left senior White House figures disillusioned with diplomacy and increasingly considering military avenues.
One British source who attended a briefing with national security adviser H.R. McMaster and other officials left feeling alarmed. "The Americans said deterrence doesn't work against North Korea and negotiation doesn't work. 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 defence strategy at the White House's National Security Council, 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. I would put the odds of them actually carrying that out at three in 10. Other policy experts say it is four in 10."
There are major uncertainties about how Kim would react if provoked. The regime has missiles that could strike Japan and South Korea.
Experts also say there is a split in the US Administration with Trump and McMaster more willing to consider military action than Rex Tillerson, the Secretary of State, and Defence Secretar Jim Mattis.