Iran is dangling the threat of a ground invasion of Kuwait to squeeze concessions out of Washington, and it is working better than the actual fighting would.

• Iranian lawmakers have floated invading Kuwait and Bahrain if US troops set foot in Iran, and Iran already ran a tiny landing on a Kuwaiti island.
• Kuwait is the easiest target: small, oil-rich, next door across a friendly strip of Iraq, and dependent on the US for defense and on desalination plants for water.
• The real goal is pain, not conquest — Iran thinks Washington cannot stomach American deaths, and 13,500 US troops sit in Kuwait.
• Iran's huge land army has been stuck on the sidelines while its navy and air power were wiped out, so hardliners want a way into the fight.
• An actual invasion would likely fail against US air power and regional allies, which is why the threat is more useful than the attack.

Outlook: An invasion is unlikely, but the threat gives Iran leverage to extract more from the US at the negotiating table, including control over the Strait of Hormuz.