President Donald Trump will formally declare Jerusalem to be Israel's capital and direct the State Department to start the process of moving the U.S. Embassy there from Tel Aviv, a historic shift of U.S. policy that could inflame key allies.

But in a sign the announcement could be more symbolic than substantive, the White House warned that any actual move would take years and that the specific boundaries of Israeli sovereignty over Jerusalem are still subject to peace talks that have bedeviled U.S. presidents for decades.

Trump's announcement about the embassy move, which is planned for Wednesday at 1 p.m. in Washington, was detailed to reporters Tuesday evening by three administration officials.