FG/Labour closed the Tehran embassy at the same time they closed the Vatican embassy. At the time I think it was claimed it was for financial reasons. But I recall speculation that the closing of the Vatican embassy was a smokescreen to cover the closure of the Tehran embassy. This is given credence IMO by the fact they later reopened the Vatican one but Tehran stayed closed. I would speculate the real reason they closed Tehran was to curry favor with America. Of course Ireland is probably now losing out on trade deals with Iran.