Besides the depletion of munitions; there is the cost factor. We’ve spent $5.6 billion in the first 2 days of the war.
https://archive.ph/JL2bC
Early Iran strikes cost $5.6 billion in munitions, Pentagon estimates
The figure, accounting for the war’s first two days, is likely to intensify concerns in Congress that U.S. forces are churning through a scarce supply of advanced weaponry.
Then there is a question about US defense industry production prowess.
General Dynamics built a factory in Texas to make 155mm artillery shells [not exactly high tech]. The new production is so bad the DOD is threatening to pull the contract.