HAMBURG — President Trump promised a long-awaited visit to London, telling U.K. Prime Minister Theresa May Saturday it was just a matter of arranging a date.

"I will be going to London," Trump declared during a meeting in Hamburg, where he attended the G-20 summit.

A visit to the United Kingdom is hardly an optional stop for a new president, given the close alliance dubbed by presidents and prime ministers alike as the "special relationship."

But Trump has been reluctant to schedule the trip in part because of threat of protests — especially in London, where Mayor Sadiq Khan has been a vociferous Trump critic.

Trump has made a trade agreement with the U.K. a higher priority, partly as a show of solidarity for British voters who chose to exit the European Union last year.

The Obama administration had chosen to put a European trade deal ahead of one with the U.K. But Trump said Saturday that a U.S.-U.K. agreement will be "done very very quickly."

"There's no country that could possibly be closer than our countries, for a long time," Trump said. "Prime Minister May and I have developed a very special relationship."

Later, in response to an entreaty by Indonesian President Joko Widodo, Trump said he'd also like to visit that country.

"We'll get there," Trump said. "It's a place I'd like to go."

Widodo seemed to be satisfied with the answer. "I can get into serious trouble if I don't bring back some good news for your millions of fans in Indonesia," he said.

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