But the PM in your country doesn't have unilateral authority to commit to military action, which is not the case in the big powers. That's the point.

Of course yes, yes in the United States the President can't declare war without Congress, but we just don't call them wars anymore.

> But the PM in your country doesn't have unilateral authority to commit to military action, which is not the case in the big powers.

They actually do:

"Constitutional convention requires that the declaration of war or commitment of British armed forces is authorised by the Prime Minister on behalf of the Crown. Parliament has no official constitutional role in the process.[7] However, ministers are still accountable to Parliament for the actions they take.[8]"

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

In practice they may not remain Prime Minister for long if they tried to use those powers in a manner that parliament wasn't happy with (unlike in the US, the UK prime minister can be deposed by parliament at any time), but in the first instance that power does lie with the PM.

But a prime minister is not remotely as powerful as a president. A prime minister has no independent power as he was not elected by the people but by the party or coalition he/she leads. That party/coalition can in principle remove the prime minister any time they want. You cannot remove a president. Look at the attempts at removal of Trump. It requires an impeachment which proved near impossible.

A vote of no-confidence is contrast is a very simple procedure.

That's very true. A PM with the backing of their party and a strong majority is very powerful, but they cannot really act unilaterally.