US President Joe Biden welcomed British Prime Minister Rishi Sunak to Washington on Thursday. It was Sunak’s first visit to the White House since taking office in October. The two had previously met several times at diplomatic events.

Sunak has been looking to reestablish ties with the European Union after the United Kingdom withdrew from the bloc. He and Biden announced a landmark deal for transatlantic cooperation.

The US-UK investment relationship is already the largest in the world. It is worth more than 1.5 trillion dollars in stock and supports nearly 3 million jobs.

Biden and Sunak said they will work together to further secure supply chains for semiconductors and critical minerals. They will also jointly develop artificial intelligence while making sure the technology is used safely.

Biden said, “We discussed how we can continue to adapt and upgrade our partnership to ensure our countries remain at the cutting edge of a rapidly changing world.”

Sunak echoed the remarks, saying, “We can shape the world once again in our pursuit of liberty, prosperity and the possibilities of a new age and that begins with our highest priority: national security.”

The two leaders said they are proud to be the “biggest contributors” to Ukraine’s military effort. The US and the UK have already agreed to provide training for Ukrainian pilots on F-16 fighter jets. However, they did not mention whether they will provide the actual aircraft.

The leaders said they will step up security in the Indo-Pacific region through their partnership with Australia known as AUKUS. Their countries are supplying the Australians with nuclear-powered submarines.

And they say they will track China’s technological capabilities, which Biden claims are being used for weapons of mass destruction and “intelligence intervention.”