Iran says a condition of release for those 15 sailors is that the US & the UK must exit Iraq. But wait, I thought Iran had nothing to do with Iraq? 
I'm getting sick of this circus. I'm feeling, as a nation, we are being humiliated while Iran makes fanciful demands like an overgrown kid. If no progress is made by Monday military action must be threatened. If no progress is made by midweek, a covert military operations should begin. If it sparks a 'war' then so be it our conscience, unlike that of Iran is clear.
While I can understand your anger and I agree that it appears the Royal Navy and Marines were NOT in Iranian waters, do you seriously believe the UK can mount a serious threat to Iran? I doubt the entire Royal Navy is capable of blockading Iran. Please don't misunderstand me, I really wish the UK could step in and kick Iran's ass but I don't think that is likely unless the independent UK nuclear deterrent is brought to bear. Go Brits... just be careful. The US is so tied down right now and so confused about what the hell we stand for I am not sure what help we can offer. You are probably better off seeking assistance from your traditional allies like Canada, Australia and New Zealand (perhaps even South Africa) than the US. You could always ask France for help but I doubt you would get THAT desperate! Besides, they won't do anything in Lebanon so why would they get involved with Iran. I wish you all the best and God Bless!
