Follow the latest updates on a key day of talks before US and North Korean leaders meet in person for first time
Mike Pompeo says the US is prepared to take actions to provide North Korea with "sufficient certainty" that denuclearisation "is not something that ends badly for them."
Mr Pompeo was briefing reporters in Singapore. He says the US is prepared to show North Korea that rather than denuclearisation posing a threat to North Korea, it's "the opposite."
Mr Pompeo won't say whether Mr Trump would consider withdrawing US troops from the Korean Peninsula.
Mr Pompeo says that US sanctions on the North will remain in place until the North denuclearises. But he says if diplomacy fails to move in the right direction, the sanctions "will increase."
Updates
5 minutes ago
Also in that briefing, Mr Pompeo said the "ultimate objective" of a historic summit with North Korea had not changed and the US was "eager to see" if North Korea was sincere about denuclearisation.
The Trump-Kim talks are expected to centre on ending the North's nuclear weapons and missile programmes in return for diplomatic and economic incentives.
Mr Pompeo said Trump was "fully prepared" for the talks, and was optimistic that the outcome would be "successful", while warning that there was still "lots of work left to do".
And he bristled at a suggestion from a reporter that the US delegation did not have the expertise required to make sufficient progress at the summit.
Mr Pompeo said the president had his "most senior expert on weapons of mass destruction" as part of the American team in Singapore.
He said the behind the scenes talks had been "moving quite rapidly".
"The United States has been fooled before," Mr Pompeo said.
"We are going to ensure that we set up a system that is robust to verify the outcomes of the summit."
American and North Korean officials are holding intensive talks in Singapore to prepare the ground for an historic first meeting between Donald Trump and Kim Jong-un.
The leaders arrived late on Sunday and both were received at the airport by Singapore’s foreign minister, Vivian Balakrishnan, before heading to their respective luxury hotels."Great to be in Singapore, excitement in the air!" Mr Trump tweeted on Monday morning. He went on to have lunch with the Singaporean prime minister at the Istana, the country's presidential palace, where he was given an early birthday cake (Mr Trump turns 72 on Thursday) and said Tuesday's meeting would be "very interesting".
Mr Kim has no official agenda for Monday, having already met prime minister Lee Hsien Loong on Sunday, hours after arriving on a plane loaned to North Korea by China.
Mr Trump and Mr Kim will meet in front of the world's media at around 9am local time on Tuesday. Any progress will have to be swift - the North Korean delegation is reportedly scheduled to leave Singapore as early as 2pm that afternoon.f