US President Donald Trump on Wednesday began a two-day state visit to the United Kingdom, marked by royal pageantry and political protests, as both sides seek to reaffirm the trans-Atlantic alliance despite sharp policy differences.

King Charles III welcomed Trump and First Lady Melania Trump at Windsor Castle with a carriage procession, honor guards and a state banquet. Trump is the first US president to be invited for a second state visit to Britain.

On Thursday, Trump will hold talks with Prime Minister Keir Starmer at Chequers, the premier’s country retreat. The agenda includes trade negotiations, technology partnerships and security issues. Nvidia CEO Jensen Huang and OpenAI chief Sam Altman are expected to join the US delegation, with reports of major US investments in UK data centers.

Tensions remain over Ukraine and Gaza. While Starmer seeks to ensure continued US backing for Kyiv, Trump has downplayed recent Russian actions in Poland. Starmer has also pledged UK recognition of a Palestinian state at the UN, a move at odds with Washington.

In London, police are bracing for large-scale demonstrations, with around 50 groups expected to rally against Trump’s visit. The Metropolitan Police said 1,600 officers will be deployed. London Mayor Sadiq Khan criticized Trump’s policies, accusing him of stoking division.

Despite protests, Windsor displayed a festive mood with US and UK flags lining the streets as crowds gathered to witness the ceremony.

Trump said trade talks will continue during his stay, as both sides aim to build on earlier tariff agreements covering autos and aerospace while seeking progress on pharmaceuticals, steel and aluminum.