PSM: "Instant detention without first investigating the merits of the accusation or no matter if hostilities are on going are the issue.Instead of calling for extradition from a country where extradition applies AFTER the merits of the accusation are adjudicated." PETER, PETER, PETER, the obligation is to deal with war criminals *as* and *when* they come within your jurisdiction. A British court therefore can't do as you suggest. Think of it this way: a British court has no obligation to go out and try to NAB a war criminal if the allegation does not involve British subjects, but they are under an obligation not to IGNORE it when a war criminal is so stupid that he blunders into their lap.
U.S., allies conduct 1 air strike in Syria and 11 in Iraq against ISIS militants (Reuters)
from the article: U.K. court defers Palestinian bid to arrest Ehud Barak