The US is burning through expensive missiles and cash faster than it can replace them, which is bad for Washington and dangerous for American troops in the Gulf.

• After five months of fighting Iran, the US has fired off a big chunk of its best missile defenses — nearly half its Patriots and over half its THAAD interceptors.
• These are the systems that protect US bases worldwide, and they take years to rebuild — supplies will stay tight through at least 2029.
• Trump pulled back on a planned escalation partly because the US is running low, even as the White House publicly denies any shortage.
• The war has cost anywhere from the Pentagon's claimed $37 billion to outside estimates near $150 billion, and the bill keeps climbing.
• The US is finally shifting to cheaper drone-killers — like $15,000 Merlin interceptors instead of $4 million Patriots — but it's late, and 18 American troops have already died.

Outlook: Congress will likely approve more war funding after summer recess, but the US keeps struggling to defend against Iran's cheap drones and missiles, so casualties and costs are set to rise.