(Reuters) -GSK said on Wednesday it plans to invest $30 billion in research and development and supply chain infrastructure in the United States over the next five years, after U.S. President Donald Trump arrived in Britain for an unprecedented second state visit to seal investment deals.

The company said its new facilities will "bridge R&D and manufacturing across both the U.S. and UK, strengthening the two countries' leadership in life sciences".

London-based GSK said the investment includes $1.2 billion for the construction of a new factory at Upper Merion, Pennsylvania, to produce new medicines for respiratory disease and cancer, with construction planned to commence in 2026.

It will also invest in AI and advanced digital technology capabilities across GSK's existing five manufacturing sites in the country, along with new drug substance manufacturing capabilities and improved device and auto-injector assembly.

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.

The $30 billion investment will help bolster R&D and clinical trial activity, and the U.S. is expected to rank first for the number of studies, sites and clinical trials participants conducted by GSK over the next five years, according to the company.

However, it did not comment on whether the $30 billion included funds that had already been earmarked for the U.S. business. But pharma industry sources have told Reuters a number of firms that have announced large U.S investments under Trump have included projects or sites already in the works in order to give a large headline figure.

GSK said it has committed about $2 billion to U.S. manufacturing over the past year, and that the investments will add hundreds of skilled jobs, on top of construction roles, and build on its roughly 15,000 strong U.S. workforce.

The U.S. accounted for nearly half of GSK's revenue last year.