> Do you think that means worldwide shipping would shut down?

I think there's a danger of that, at least if countermeasures are not easily available for normal shipping.

Even 1-on-1 rather than 1-v-everyone, there's too many players (not all of them nations) with too many conflicting goals and interests. If Cuba tried to do it, could they credibly threaten to sink all sea-based trade involving the USA? If not Cuba, who would be the smallest nation that could?

And the same applies to Taiwan and China, in both directions, either of which would be fairly dramatic on the world stage, even though China also has land options. Or North Korea putting up an effective anti-shipping blockade against Japan.

> But to a level where military escorts can feel safe.

Are there enough military ships to do the escorting?

The current situation is very dangerous. A global disruption in shipping would lead to an economic crisis that could start WW3 (imo).

Also the US and Europe would be pretty fucked since we depend on it much more.

China could still get resources from russia and is much more self sustained.

Also China and Russia want to break the us hegemony.

> I think there's a danger of that, at least if countermeasures are not easily available

Note that the era of free navigation is recent and short. Countermeasures would certainly emerge. But shipping wouldn’t stop.

> Are there enough military ships to do the escorting?

For critical passage, yes. If Iran is just taking pot shots at any ships anywhere, you basically have to actually blockade it.