Yup, deterrence theory is quite interesting and every country has different strategies. One doesn't need hundreds of nukes to deter an enemy from nuking them.

For example is a large difference between massive retaliation [1] which the US uses to deter North Korea, and minimal deterrence [2] used by China (during the cold war), or Pakistan currently.

Secondly it's not just the amount of nukes that influences deterrence, it's how one says they will use them. For example China has pledged "no first use" from the moment they got their first nuclear weapons, whereas the Russia and the US both adopted official policies stating the right of first use.

[1] https://en.wikipedia.org/wiki/Massive_retaliation

[2] https://en.wikipedia.org/wiki/Minimal_deterrence

I did not know submarines could carry 150 weapons. Wow, that is a lot.

Modern ballistic missiles have multiple independent warheads. For example the French M51 has "6 to 10" independently targetable warheads. The submarine carries "only" 16 of these missiles.

https://en.wikipedia.org/wiki/Multiple_independently_targeta...