U.S. national security adviser John Bolton arrived in the U.K. on Sunday for two days of talks with the new British government about more closely aligning the countries’ interests on global challenges, including Brexit, a rising China and tensions with Iran.

Bolton specifically plans to make the case for Britain to declare the 2015 Iran nuclear deal as dead, a senior administration official said. Trump withdrew the U.S. from the deal last year, while the U.K., Germany and France have worked to preserve it.

With freshly-elected British Prime Minister Boris Johnson promising a U.K. withdrawal from the European Union by October 31, the U.S. is intensifying its preparations for such a move. Bolton’s trip to London is aimed at ensuring — and, where possible, enhancing — defense and trade cooperation between the two countries under the new government and a looming Brexit.

The White House hopes Trump’s close relationship with Johnson helps bend Britain’s approach on key foreign policy issues toward the president’s, the official said. Trump frequently speaks with Johnson, said the official, describing Johnson’s predecessor, Theresa May, as centrist and the new prime minister as center-right.

Bolton, who was invited to London by his British counterpart Mark Sedwill, is not scheduled to meet with Johnson, the senior administration official said. But the official said he does plan to meet with some of the prime minister’s top aides, members of Parliament, conservative political figures, the new defense secretary and a top official on international trade.

Trade negotiations between the U.S. and U.K. are focused on how quickly the two countries can achieve a comprehensive agreement, and whether they can make headway on individual sectors in the meantime, the official said.

He’ll also press for the U.K. not just to reduce but cut entirely its use of equipment from Huawei, the Chinese telecommunications company the U.S. has accused of being an arm of the Chinese government and a national security threat, according to the official.

The request comes as the U.S. is locked in an escalating trade war with China. The senior administration official said the White House is preparing for resumed talks with China in September but expressed doubt that Beijing is prepared to make significant commitments, such as stopping intellectual property theft and discrimination against U.S. businesses.