Pay attention to US-UK rapport, Rex Tillerson says
The US and the UK need to "pay attention" to their "treasured" relationship, the US secretary of state said as he visited London.
"Sometimes we forget about the importance of our own relationship," said Rex Tillerson, who held talks with UK Foreign Secretary Boris Johnson.
Donald Trump recently cancelled a visit to the UK, criticising the new US embassy in London.
He also clashed with Theresa May after retweeting a far-right group's videos.
The two leaders are due to meet this week at the World Economic Forum in Davos.
At a press conference, Mr Tillerson said he treasured his relationship with Mr Johnson.
"We spend a lot of time talking about the world's problems - sometimes we forget about the importance of our own relationship," he said, adding: "We need to pay attention to that relationship and the importance of this relationship on a bilateral basis as well."
Mr Tillerson also met UK Prime Minister Theresa May, and the Iran nuclear deal - which has been heavily criticised by Mr Trump - was on the agenda.
Downing Street said Mrs May reaffirmed the UK's commitment to the deal, which suspends sanctions in return for a reduction in Iran's nuclear activity.
Mr Tillerson said "flaws" in the deal could be fixed by working groups and a possible "side agreement".
"We will be discussing that through working groups beginning as early as next week and we will see what progress we can make," he said.
Mr Johnson said there was a "wide measure of agreement" on the European side on the need to work collectively to constrain Iranian ballistic missile activity.
"We think we can do that. We think we can do that together," he said.
Mr Tillerson also visited the relocated US embassy.
Mr Trump said he had cancelled a visit to the UK In February because he was not a "big fan" of the new embassy - which is moving from Mayfair to south London - and had refused to "cut the ribbon".