JERUSALEM — For years, Palestinians in the crowded East Jerusalem neighborhood of Silwan have complained that the walls of their homes were settling and cracking, disturbed by an underground archaeological dig led by a right-wing Jewish settler group.

On Sunday, when that dig was officially unveiled, not with a ribbon-cutting but with the ceremonial smashing of a brick wall, it was President Trump’s ambassador to Israel, David M. Friedman, who swung the first sledgehammer.

The reverberations were literal and metaphorical.

American ambassadors to Israel, to avoid being seen as taking Israel’s side in the conflict with the Palestinians, have long avoided public appearances in East Jerusalem. Israel captured East Jerusalem from Jordan in 1967 and then annexed it. Most of the world considers it illegally occupied, and the Palestinians want it as the capital of a future state.

But Mr. Friedman has pulverized diplomatic barriers before. In October, he attended a business conference in the West Bank settlement of Ariel, reportedly the first official visit to a Jewish settlement by an American ambassador.