LONDON — 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.

In addition to agreement on Iran, the senior administration official said the White House is seeking a more aligned policy with the U.K. in the Middle East broadly.

Bolton plans to seek assurances on the U.K.’s commitment to helping establish a multilateral force and a safe zone in northern Syria, the official said, and will discuss efforts to achieve a nuclear strategic arms treaty.

The White House is concerned that a ceasefire in Idlib could fall apart in coming days and is closely watching the conflict, the official said. The official credited the U.S.’s continued presence in northeastern Syria with Turkey’s decision not to cross the border into the area. If Turkey were to cross the border, the official said, the administration would accelerate its decision on adopting new sanctions on Ankara in response for its purchase of a Russian missile defense system.

Trump has delayed the sanctions, which his aides and Republican and Democratic lawmakers have pressed him to implement, out of concern about Turkey retaliating, administration officials have said. The senior administration official briefing on Bolton’s trip to London set the timeline for a decision as sometime in the next couple months. The president has been the lone holdout on sanctions, the official said.

The official predicted the new British government will be tougher on business conducted with Iran and welcomed the prime minister’s decision to join a U.S.-led patrol effort in the Persian Gulf to secure passage in the Strait of Hormuz, known as Operation Sentinel. That operation is still a couple of weeks away from coming together, the official said. And the White House doesn’t expect a the U.K. to make a decision on the nuclear deal during Bolton’s visit, according to the official.