A US–Saudi civilian nuclear deal is stirring big regional stakes, and it's mostly good for Trump and Saudi Arabia but bad for Iran.

• The US and Saudi Arabia signed a 30-year nuclear cooperation deal, with US companies getting first crack at building Saudi reactors.
• Trump says the deal only goes through if Saudi Arabia recognizes Israel and joins the Abraham Accords, and that there will be no uranium enrichment.
• The rollout was messy — it leaked early, angered the White House, and the Saudis say they never agreed to fully join the Abraham Accords.
• Israel is wary of any Saudi step toward nuclear power, but sees Saudi Arabia as a more stable partner than Iran, the real target here.
• Turkey (with Russia's help), Egypt, and possibly Qatar are watching and may push for their own deals, raising fears of a nuclear arms race.

Outlook: The deal now goes to Congress, and expect more Middle East countries to angle for similar terms while Iran stays boxed out.