About 50,000 people are planning to demonstrate in London alone on Friday, the day when Trump has meetings planned with both Prime Minister Theresa May and Queen Elizabeth II in the countryside. Protesters are also expected to show up at Chequers, the prime minister’s country residence, and Windsor Castle.

The embassy cautioned people to be aware of their surroundings and “exercise caution if unexpectedly in the vicinity of large gatherings that may become violent.”

Democrats Abroad, the official overseas wing of the Democratic Party, countered the embassy’s messaging, calling upon Americans living in the U.K. to come out in full force on Friday.