Support for Ukraine will top the agenda when Lord Cameron makes his first visit to the US as Foreign Secretary.
He will arrive in Washington later for a two-day visit, as world leaders grapple with the ongoing battle in Ukraine as well as the escalating crisis in Gaza.
The visit comes at a crunch time for Kyiv, with concerns about the provision of US military aid amid deep divisions in Congress about new funding and support.
The Foreign Secretary is expected to meet US secretary of state Antony Blinken and Republican and Democratic congressional leaders as part of the trip.
Ahead of the Washington visit, Lord Cameron announced a £37 million package of winter humanitarian support for the country as it continues to fight Russian President Vladimir Putin’s forces.
The crisis in the Middle East will also top discussions, as Israel widens its offensive into southern Gaza amid growing fears about the fate of civilians.
Lord Cameron said: “The UK and the US are deeply bound by a shared mission to defend the values that provide security and prosperity for us all.
“That is why we remain unwavering in our support of Ukraine. If we allow Putin’s aggression to succeed, it will embolden those who challenge democracy and threaten our way of life. We cannot let them prevail.
“We also stand united in the Middle East, working together to ensure long-term security and stability in the region, and in responding to the challenges posed by China.”
The Foreign Office said that the UK on Wednesday would also impose new sanctions to target foreign military suppliers it accused of “propping up Putin’s war machine” with exports of equipment to Russia.
Earlier Defence Secretary Grant Shapps said that the world cannot get “bored” with the conflict in Ukraine, nearly two years on from the Russian invasion.
He told ITV News: “I accept it is unlikely to be a quick conclusion but I also passionately believe that we cannot afford, and of course the Ukrainians can’t, a Putin win.
“We cannot have a situation in the 21st century where an autocratic leader thinks it is OK to invade a democratic neighbour and the rest of the world will just give up and get bored of it.”