Foreign Secretary William Hague yesterday hailed the "unbreakable alliance" between Britain and the US following talks with Secretary of State Hillary Clinton in Washington.
On his first trip abroad since being appointed to head the Foreign Office on Tuesday, Mr Hague said the US was "without doubt the most important ally of the UK" and welcomed President Barack Obama's description of the "extraordinary special relationship" between the two countries.
In a joint press conference following talks dominated by Afghanistan, Iran and the economic crisis in the eurozone, Mrs Clinton said she was "very intrigued" by the outcome of last week's election in the UK.
And she said the Obama administration was looking forward to "working with the new British government".
Mrs Clinton said that the General Election and the smooth transfer of power to the new coalition government in the UK were "two powerful symbols of the enduring democratic traditions that our two nations share".
Mrs Clinton said that during yesterday's talks Mr Hague reaffirmed Britain's commitment to working with the international community and the Afghan people to achieve long-term stability in the country.
And she said: "The US is deeply appreciative of the British contribution in Afghanistan and we honour the sacrifices of the British service members who serve their country with such distinction overseas."
The UK and US are "firmly committed" to the Nato mission and support the efforts of Afghan President Hamid Karzai - due to visit the UK today for talks with Prime Minister David Cameron - to fight corruption and build a stable and strong government, she said.
Mrs Clinton said Britain and the US remain "united in our insistence that Iran fulfil its international obligations and prove its nuclear programme is for peaceful purposes only".
The UK and US are together seeking a United Nations Security Council resolution threatening serious consequences if Iran continues to flout the wishes of the international community. Mr Hague said the resolution should send "a strong and united signal about Iran's nuclear programme".
Mr Hague said that he and Mr Cameron were struck, after taking office, by the "sheer warmth of the welcome we have had from the United States". President Obama, Mrs Clinton and Vice-President Joe Biden were the first foreign dignitaries to call to congratulate their opposite numbers in the UK after the coalition government was formed.
Mr Hague described yesterday's talks as "very positive" and confirmed that Mr Cameron was making Afghanistan his "top priority" in foreign affairs.