Donald Trump has ticked off a key policy promise by declaring Jerusalem the capital of Israel.
It's important to the President to be seen to be delivering on the things that he said he would do, even if, in this case, the decision goes against the advice of several of his key advisers and the bulk of the international community.
The fact that successive US presidents have also campaigned on the issue and then reversed their plans once in office also makes this a key milestone for a President who will regard it as a symbol of his relative superiority as a leader.
He's also satisfying his wealthy Jewish donors who have long been in favour of moving the US embassy from Tel Aviv to Jerusalem.
There are several qualifiers in today's announcement. Moving the US embassy from Tel Aviv will take at least three years. The President will have to sign waivers every six months to keep it in Tel Aviv in the meantime, so nothing changes immediately. And he may well be out of office by the time the move happens, unless he wins a second term.
All that means that this is a largely symbolic announcement. But symbols can be powerful.
Several high-profile Republicans have welcomed the move, echoing Donald Trump's sentiments that, practically, Jerusalem is already the capital of Israel as the seat of the government, the courts and the residence of the Israeli Prime Minister.
There's a prevailing view that being cowed by the threat of Arab fury by keeping the embassy in Tel Aviv has been of no material benefit to the Israeli-Palestinian peace process.
That may well be true, but moving it will have a cost.
There may well be mass protests, violent riots or worse. US embassies and their staff have been put on alert across the region and around the world.
Palestinians, and their allies, read this as a version of giving Jerusalem to the Israelis, discounting their own historic claim to the capital and cementing their deep sense of persecution.
It will strain the US's ties with its own Arab allies and undermine diplomatic efforts to bring about peace in the Middle East.
Donald Trump's son-in-law Jared Kushner has been tasked with making that happen. The President has previously said that such a result is "maybe, not as difficult as people have thought over the years".
On that, Donald Trump has now sabotaged himself.
Having taken a side, America will not be regarded as an honest broker.