I don't know enough about the current state of naval warfare but I've assumed this is related to the asymmetry that's emerged around protecting capital warships, especially in the scenario of a very narrow strait and a long enemy-controlled coastline. They can shoot relatively low-cost, short-range guided missiles from anywhere along the coast. Even if a warship stops the vast majority of them, only one has to get through to sink a multi-billion dollar ship that takes a decade to replace.

There are now similar asymmetries emerging across war-fighting and even though warships can still be effective (and less vulnerable) in other scenarios, this specific one seems especially bad. The other factor is that most of what ships carry through the straight isn't going directly to the U.S. so the impact on the U.S. is mostly secondary, reducing the risk the U.S. is willing to take. Of course, all this was known beforehand by military strategists which makes this all look even worse for the U.S. administration.

Modern US surface warships such as the DDG-52 Arleigh Burke class are pretty survivable. The Iranians (and their Houthi proxies) have made sustained attacks on them and don't seem to have hit anything. And a single hit would be highly unlikely to sink such as vessel: we're not talking about something like the Russian Moskva cruiser that was crewed by drunks and had inoperative defensive systems.

The real problem is that there are too few such vessels to sustain convoy escort operations. Each destroyer can only provide area air defense for a handful of merchant vessels, and they can only stay on station for a few days at a time before they have to cycle out to refuel, rearm, and conduct critical maintenance. Some of the key munitions also appear to running low. And it appears that the other Gulf states are refusing to allow use of their facilities over fears of Iranian retaliation.

Other countries generally aren't really in a position to assist as part of a coalition either. They either don't have sufficiently capable warships at all, or lack the logistics train to sustain them in the Persian Gulf / Gulf of Oman region. After the Cold War a lot of countries like the UK and Germany essentially dismantled their navies so that they now exist only as government jobs programs.

> I don't know enough about the current state of naval warfare but I've assumed this is related to the asymmetry that's emerged around protecting capital warships, especially in the scenario of a very narrow strait and a long enemy-controlled coastline.

It's not the billion-dollar warships that transport oil, it's the much more fragile and unarmed tankers.

Even if the US Navy begins full escort duty, it can't remain on-station forever. What are shippers to do afterwards? One drone strike might cause a tanker to have a very bad day, yet it's extremely difficult to so permanently degrade an entire country that they become incapable of launching sporadic attacks.

Ultimately, the status of the Strait must be settled diplomatically, and the US and Iran are each betting that the other side will blink first.

All of this was well known before the war though. The idea that navy is incredibly vulnerable modern anti-ship defenses has been a major consideration in the Taiwan situation for at least a decade (mostly in relation to the ability of the US navy to even operate in the area in a war). More recently, Ukraine has made a great show of sinking navy ships with cheap unmanned surface vehicles

Back in WWII you could sail your navy up a river and expect positive results. In the 21st century, the idea of attacking an enemy-held strait with navy doesn't work

Cheap drones taking out an AWACS is a great example of this. The US has only 16 of these and it will cost $700 million to replace, and was taken out by a drone that probably cost less than your car.

suppose one has N independently developed interception systems (from detection till physical interception attempt), each with an intercept success rate of 90%.

a rudimentary calculation then gives the probability of hitting (not sinking) the ship as 0.1^N per launched missile; so it seems that given enough budget to spend on independently developed missile interception systems allows to drive down the penetration success rate arbitrarily.

Multi-billion sounds like $ 10^10; so assuming an attacker can launch say a million missile attempts then the statistical loss would be 0.1^N * 10^10 * 10^6; so the statistical loss can be driven down arbitrarily say to $ 1 by developing ~ 16 independent interception systems.

16 independently developed intercept systems doesn't sound like unobtainium for a vested nuclear power.

The US military is also just less powerful than it was at its peak at the end of the Cold War as well.

Still the most powerful navy in the world, but spread increasingly thin (turns out "the whole world" is quite a big place).

This is no longer Reagan's (almost) 600 ship navy, and projecting power halfway round the world is no mean feat when your opponent can lob missiles and drones at you from their back garden

> Even if a warship stops the vast majority of them, only one has to get through to sink a multi-billion dollar ship that takes a decade to replace.

Even worse. They don't need to attack _warships_. They can just attack civilian vessels, especially tanker ships, that don't have any defenses.

A hit on a tanker and the subsequent oil spill would be catastrophic.