America's new Secretary of State John Kerry will hold talks with the Prime Minister and Foreign Secretary William Hague on the first stop in an 11-day world tour.
The conflict in Syria, nuclear stand-off with Iran and Middle East peace process are expected to be high on the agenda.
But the Falklands is also likely to come up - with Washington under pressure to recognise the result of a referendum next month on whether the islanders want to remain British.
More top news
Rolls-Royce is a company whose fortunes should interest you. So don't be sucked in by the reporting of its first dividend cut in 25 years.
New plan for buyers to be notified when dangerous goods need to be recalled after reports of hundreds of fires caused by tumble dryers.
A junior doctor launches a scathing attack on Health Secretary saying: "Sc*** you Jeremy Hunt, you've picked a fight with the wrong crowd".