(Reuters) - Drugmaker GSK said Wednesday it would invest $30 billion in U.S. research and development and supply chain infrastructure over five years, after U.S. President Donald Trump arrived in Britain for a second state visit to seal investment deals.

The company said its new facilities in the U.S., which made up half its revenue last year, would "bridge R&D and manufacturing across both the U.S. and UK, strengthening the two countries' leadership in life sciences."

GSK's investment includes $1.2 billion to build a new factory in Pennsylvania that will produce new medicines for respiratory disease and cancer, with construction to commence in 2026.

It will invest in AI, digital technology, new drug substance manufacturing, and improved device assembly at GSK's five U.S. sites.

London-based GSK is the latest drugmaker to scale up its U.S. footprint as Trump threatens to impose import tariffs on the industry and seeks to boost domestic manufacturing. The sector has historically been spared from trade disputes.

"This landmark investment will create tens of thousands of American jobs and ensure that critical medicines and technologies are developed and manufactured right here on U.S. soil-where they belong," U.S. Commerce Secretary Howard Lutnick said in a statement shared by GSK.

British Prime Minister Keir Starmer said in the statement that the investment was a "powerful example of how UK-U.S. collaboration was driving real-world impact - improving people's health, creating opportunity, and turbocharging growth."

The GSK investment in the United States comes as some drugmakers, including AstraZeneca and U.S. drugmaker Merck & Co, have pulled back or paused investments in the UK, citing a challenging domestic environment.

CLINICAL TRIALS, R&D TO GET BOOST

The investment will bolster R&D and clinical trial activity, and the U.S. is expected to rank first for the number of studies, sites and clinical trial participants conducted by GSK over the next five years, the company said.

The drugmaker did not say whether the $30 billion included funds already earmarked for its U.S. business.

Pharma industry sources have told Reuters that some firms that have announced large U.S investments under Trump have included projects or sites already in the works in order to provide a large headline figure.

GSK said it had committed about $2 billion to U.S. manufacturing over the past year, which would add hundreds of skilled jobs as well as construction roles, building on its roughly 15,000 strong U.S. workforce.