On his first foreign business trip as prime ministerMs. Truss flew overnight to the States for the annual United Nations General Assembly (UNGA).
The visit will include a number of meetings, including with EU representative Ursula von der Leyen, and a speech to world leaders. It comes as political action resumes after a period of national mourning for the Queen.
Ms Truss hopes the focus will be on energy security and fighting Russia’s war in Ukraine, but clashes around Northern Ireland A protocol is associated with a function.
Mr Biden, the US president of proud Irish descent, expressed concern about the threat Brexit posed to the peace process and played down the chances of a free trade deal.
His French counterpart, Mr Macron, has long been a critic of Brexit and has insisted strongly that Britain honors commitments on Northern Ireland and fishing rights.
Ms Truss sparked a diplomatic row during the Tory leadership contest when she refused to give a clear answer to a question about whether the president of an allied country was “friend or foe”.
Instead, the then foreign minister said last month there was “no jury”.
Ahead of the visit, the Prime Minister’s spokesman described France as a “long-standing ally” and insisted that relations between London and Paris, as well as with the EU, were “good”.
Asked if the meeting with Macron would be awkward, the spokesman said: “No, the prime minister wants to build a constructive relationship with President Macron.”
But the spokesman maintained his stance on the controversial Northern Ireland Protocol bill, which the EU and others say will breach international law.
Ms Truss will meet Mr Macron on Tuesday before meeting Mr Biden on Wednesday. She was due to speak to the US president in Britain last weekend when he arrived for the Queen’s funeral, but the meeting was postponed.
She is not scheduled to be admitted to the White House, which was visited by Boris Johnson during his visit to Unga last year.
Meetings with the leaders of Turkey, Spain and Israel are also expected, and Ms Truss will warn that now is not the time to “take your foot off the gas” in opposing Vladimir Putin’s invasion of Ukraine.
Before leaving the States on Wednesday night, Ms Truss will use her summit speech to say that Britain under her leadership will be an “active defender of our democratic values” and will work to counter authoritarianism with allies.
The trip kicks off a frenetic few days of political action in Ms Truss’s young premiership, with details of how companies will be helped in the energy crisis and a major announcement on NHS bills.
Ms Truss, who was joined in the US by Foreign Secretary James Cleverley, will return ahead of Chancellor Kwasi Kwarteng’s mini-budget on Friday.