Jersusalem and it's status, whether the sole capital of Israel or somehow shared in a two state solution, that needs to be negotiated. Every one of Trump's predecessors was walking a tightrope between supporting Israel and not inflaming Palestinians and their allies, some of which are also American allies. It's a powderkeg, and Trump seems intent on kicking it. The defense for this approach appears to be that being cautious hasn't worked, so let's try belligerence.
What has become obvious is that Trump is not the negotiator he has portrayed himself to be. He has solved nothing, and has passed nothing of importance. What his supporters think is him playing 4D chess while the rest of the world is stuck in 2D mode, looks too much like chaos and lack of planning or vision to be thought of as anything else.
Yes, the intention has been that Jerusalem would be the capital of Israel and the location for the American embassy. But not by decree. This is the most highly disputed piece of real estate on the planet, having been fought over for thousands of years by warring religious factions. By clearly taking one side, America relinquishes its leadership role in brokering a solution, and needlessly creates more enemies for itself. Remember, when Israel was created in 1947, the U.S. wouldn't even *sell* arms to them.
Yes, the intent was always to move the embassy, but not unilaterally. That's the difference here, and it's a key difference. This is announcing you're taking something off the negotiating table without giving anything back. This is not negotiation, and it will play badly in the Arab world and will get people needlessly killed, when it will likely just end up back as part of negotiations anyway, just as a starting point to restart negotiations.
This is only a gift to right-wing Jews, who don't even make up the majority of Jews in Israel, and to fundamentalist Christian American nutcases who are happy about the prospect of ushering in Armageddon. This is a play to rally his base, who are not at risk, at the expense of people on the other side of the world his base don't really care about and couldn't find on a map, who are.
