You can be sure it would have triggered a major international storm, stentorian declarations about the threat of state-sponsored terrorism, and perhaps a debate at the UN security council, with demands for harsher sanctions against an increasingly dangerous Islamic republic.
Substitute Israel for Iran, and the first part of that scenario is exactly what happened in Dubai last month. A senior Hamas official, Mahmoud al-Mabhouh, was murdered in his hotel room in what was widely assumed from the start to be an operation by the Israeli intelligence service Mossad. Less than a month later, strong suspicion has turned to as good as certainty with the revelation that the hit team had used the passport identities of six Britons with dual nationality and currently living in Israel.
But instead of setting off a diplomatic backlash, the British government sat on its hands for almost a week after it was reportedly first passed details of the passport abuse. And while the Foreign Office finally summoned the Israeli ambassador to "share information", rather than protest, Gordon Brown could yesterday only promise a "full investigation".
In parallel with this languid official response, most of the British media has treated the assassination more as a ripping spy yarn than a bloody scandal which has put British citizens at greater risk by association with Mossad death squads. It was an "audacious hit", the Daily Mail enthused, straight out of a "Frederick Forsyth page-turner", while the Times revelled in an attack that resembled nothing so much as a "well-plotted murder mystery".
Running throughout all this is a breathless awe at Mossad's reputation for ruthless brilliance in seeking out and destroying Israel's enemies. In reality, the Dubai operation was badly bungled, as the Israeli press has already started to acknowledge. Despite having the relatively easy target of an unarmed man in a luxury hotel in a non-hostile Gulf state, Mossad managed to get its agents repeatedly caught on CCTV and effectively exposed Israel's responsibility through the hamfisted passport scam.