<h1>US president's UK state visit yields major science and technology investment pledges, AI and quantum projects, but tariffs unresolved</h1> The US president completed a state visit to the UK marked by ceremonial honours and a bilateral science and technology agreement promising substantial investment commitments and jobs, including major AI and quantum projects and cross-Atlantic corporate pledges. Formal cooperation and private talks addressed Ukraine, Gaza, immigration and US tariffs on UK steel and aluminum, but significant tariff reductions remain unresolved. Differences arose over Palestinian state recognition and immigration policy; discussion of additional Russia sanctions produced no concrete outcomes. Security authorities made a small arrest over a publicity stunt targeting the visit; broader legal or treaty changes were not announced.