At the weekend, French police discovered a bomb in a vehicle in which two ethnic Iranian Belgians had travelled from Belgium to Paris. In what was clearly a Europe-wide intelligence-led operation, German police also arrested an Iranian diplomat serving in Vienna and the Austrian government set about removing his diplomatic immunity.

The target for the bombers appears to have been a large gathering of opponents of the ayatollahs in the French capital at the weekend. The National Council of Resistance of Iran (NCRI) styles itself as a parliament in exile. A number of its leaders live in Paris. The asylum France has granted to these Iranian exiles has long vexed the regime in Tehran, just as the Shah of Iran complained regularly that the French had given shelter to Ruhollah Khomeini, the cleric who ultimately overthrew his Pahlavi dynasty.

Though appearing to concede that this was a terrorist attack, the Iranian government has, of course, denied any involvement in the planned bombing. One official even suggested that the exiles were planning to blow themselves up to attract media attention. And Tehran absolutely insists that its arrested diplomat, identified as Assadollah Assadi, was in no way involved in the plot. European intelligence sources have leaked that Assadi had been head of the Vienna embassy’s VEVAK intelligence station for the past four years.

Given the extreme likelihood that Tehran was indeed behind this thwarted bomb attack, what is so interesting is its timing. It was to have occurred 48 hours before President Hassan Rouhani was due to land in Vienna for talks on keeping alive the 2015 Geneva nuclear deal, which President Trump has torn up.

As the urbane and acceptable face of the violent clerical regime, Rouhani’s job was to try and convince the Europeans to break ranks with Washington and refuse to join in the planned reintroduction of sanctions. It has long been clear that many European politicians were prepared to hold their noses and do what they hoped would be lucrative business, helping the ayatollahs to rebuild their wrecked economy. But Trump appears perfectly prepared to also sanction any international company that continues to trade with Iran. No European multinational is going to risk its worldwide position with the Americans for the sake of a few Iranian deals, however alluring they might normally be.

Had a bomb exploded at the NCRI rally in the Paris Convention Center, in the light of previous horrific terrorist attacks in Paris, Nice, Brussels, Madrid and London, the fury of the Europeans would have been considerable. Even as it is, the unmasking of this conspiracy was sure to make Rouhani’s sweet-talking much more difficult.

Was this a blunder by the spy chiefs of VEVAK or a deliberate attempt by hardliners to sabotage president Rouhani’s mission, so that Iranian nuclear scientists can carry on openly with their weapons development program which, despite the Geneva deal, they have been continuing in secret? It is more probably the latter. The hardline core of the regime in Tehran is intent on projecting its power by interfering openly and devastatingly in the affairs of its Arab neighbors. If Moscow can murder its opponents at home and abroad and deny any responsibility, why should not Tehran follow suit? Loudly protesting innocence is a remarkably effective way of emphasizing the extent of a regime’s sinister and deadly reach.