You would have better experience to know if this would happen, kabar. I'm on the outside, and it looks as though the US is willing to change the rules of engagement. Not violating international law, but in changing the way in which the situation is handled.
rodguy911 points out that the direct response rests with the UK
There is no doubt that the ball is in the UK's court, but if the Iranians demand that the five Revolutionary Guards held by us/Iraq be released as a condition for the release of the UK sailors, then we will be involved indirectly. I can see an exchange being made, but not connected so as both sides can save face.