I'm British, of course I do!
Mate, all states have unlimited liberty of action. Treaties, international law, the UN.....it's all just paper, smoke and mirrors. Any country can do whatever it likes at any time, there will just be consequences.
The consequences, for example, of Cuba sending out privateers to harrass American shipping would, I daresay, be a carrier battle group parked outside Guantanamo Bay with orders to sink anything not flying the stars and stripes. So they don't do that.
The consequences of Britain capturing and sinking a Somali vessel strongly suspected (but not proven) of committing acts of piracy are........um.........gimme a min, I'm sure I'll think of something.