Boris Johnson is to appear on Donald Trump's favourite TV show as he attempts to save the Iran nuclear deal.
The foreign secretary is in the US as part of a last-ditch effort to convince the president not to pull out of the accord.
During his two-day visit, Mr Johnson is expected to appear on the Fox & Friends morning news show, which Mr Trump is known to avidly watch.
The US president has criticised the Iran nuclear agreement and in January issued an ultimatum to "either fix the deal's disastrous flaws, or the United States will withdraw".
The Iran nuclear deal eased sanctions on Tehran in exchange for commitments to abandon its nuclear weapons programme.
Mr Johnson wrote in the New York Times that "only Iran would gain" from abandoning the agreement.
The president has threatened to withdraw from the Joint Comprehensive Plan of Action (JCPOA) deal signed by the US, China, Russia, Germany, France and Britain with Iran in 2015.
He will decide on Friday whether to to reimpose sanctions and effectively scrap the deal.
Mr Johnson wrote in article for the New York Times: "Of all the options we have for ensuring that Iran never gets a nuclear weapon, this pact offers the fewest disadvantages.
"It has weaknesses, certainly, but I am convinced they can be remedied.
"Indeed at this moment Britain is working alongside the Trump administration and our French and German allies to ensure that they are."
British, French and German diplomats have been working for weeks behind the scenes with US counterparts in an effort to preserve the deal.
Mr Johnson said the deal had put restrictions on Iran's nuclear programme and added that "now that these handcuffs are in place, I see no possible advantage in casting them aside".
He also warned: "Only Iran would gain from abandoning the restrictions on its nuclear programme."
The foreign secretary continued: "At this delicate juncture, it would be a mistake to walk away from the nuclear agreement and remove the restraints that it places on Iran."
Mr Johnson will also hold talks with senior administration officials including vice president Mike Pence and national security adviser John Bolton.
He is also expected to discuss North Korea ahead of Mr Trump's planned meeting with leader Kim Jong Un.
The UK's ambassador to the United States, Sir Kim Darroch, said the Iran agreement was "a good deal" but efforts were ongoing to "find some language, produce some action that meets the president's concerns".
The ambassador also insisted that Mr Trump's controversial comments about knife crime in London would not damage relations ahead of his visit to the UK in July.
The Iranian foreign minister Mohammad Zarif said on Monday that Tehran's "fierce reaction" will "not be pleasant for the US" if it abandons the nuclear deal.
The country's foreign ministry spokesman Bahram Qasemi added that the the US will pay a "heavy price".
Iranian president Hassan Rouhani has warned the US will suffer "historic remorse" if Mr Trump pulls out of the deal.
He said in a televised speech: "We have plans to resist any decision by Trump on the nuclear accord.
More from Boris Johnson
"Orders have been issued to our atomic energy organisation and to the economic sector to confront America's plots against our country.
"America is making a mistake if it leaves the nuclear accord."
Boris Johnson is to appear on Donald Trump's favourite TV show as he attempts to save the Iran nuclear deal.
The foreign secretary is in the US as part of a last-ditch effort to convince the president not to pull out of the accord.
During his two-day visit, Mr Johnson is expected to appear on the Fox & Friends morning news show, which Mr Trump is known to avidly watch.
The US president has criticised the Iran nuclear agreement and in January issued an ultimatum to "either fix the deal's disastrous flaws, or the United States will withdraw".
The Iran nuclear deal eased sanctions on Tehran in exchange for commitments to abandon its nuclear weapons programme.
Mr Johnson wrote in the New York Times that "only Iran would gain" from abandoning the agreement.
The president has threatened to withdraw from the Joint Comprehensive Plan of Action (JCPOA) deal signed by the US, China, Russia, Germany, France and Britain with Iran in 2015.
He will decide on Friday whether to to reimpose sanctions and effectively scrap the deal.
Mr Johnson wrote in article for the New York Times: "Of all the options we have for ensuring that Iran never gets a nuclear weapon, this pact offers the fewest disadvantages.
"It has weaknesses, certainly, but I am convinced they can be remedied.
"Indeed at this moment Britain is working alongside the Trump administration and our French and German allies to ensure that they are."
British, French and German diplomats have been working for weeks behind the scenes with US counterparts in an effort to preserve the deal.
Mr Johnson said the deal had put restrictions on Iran's nuclear programme and added that "now that these handcuffs are in place, I see no possible advantage in casting them aside".
He also warned: "Only Iran would gain from abandoning the restrictions on its nuclear programme."
The foreign secretary continued: "At this delicate juncture, it would be a mistake to walk away from the nuclear agreement and remove the restraints that it places on Iran."
Mr Johnson will also hold talks with senior administration officials including vice president Mike Pence and national security adviser John Bolton.
He is also expected to discuss North Korea ahead of Mr Trump's planned meeting with leader Kim Jong Un.
The UK's ambassador to the United States, Sir Kim Darroch, said the Iran agreement was "a good deal" but efforts were ongoing to "find some language, produce some action that meets the president's concerns".
The ambassador also insisted that Mr Trump's controversial comments about knife crime in London would not damage relations ahead of his visit to the UK in July.
The Iranian foreign minister Mohammad Zarif said on Monday that Tehran's "fierce reaction" will "not be pleasant for the US" if it abandons the nuclear deal.
The country's foreign ministry spokesman Bahram Qasemi added that the the US will pay a "heavy price".
Iranian president Hassan Rouhani has warned the US will suffer "historic remorse" if Mr Trump pulls out of the deal.
He said in a televised speech: "We have plans to resist any decision by Trump on the nuclear accord.
More from Boris Johnson
"Orders have been issued to our atomic energy organisation and to the economic sector to confront America's plots against our country.
"America is making a mistake if it leaves the nuclear accord."
