Hangershuffle,
Any action taken by any of HM Forces in your hypothetical scenario would be taken within carefully scripted ROE agreed and authorized by the international community/UN. The commander of such forces authorizing use of lethal force would be well versed in those ROEs as would the crews. The answer to your question then needs to be addressed to what those ROEs would be. Open pursuit of those who have surrendered or are not in the immediate act of endangering life would be unlikely. Not really much different to the armed guard situation at most stns.