Vladimir Putin’s image in Russia as a man of action has been carefully crafted over the years and he was given an opportunity to play the role in Germany today.

Hours before his press conference with Angela Merkel, the German Chancellor, Kremlin officials in Iran and Germany suddenly began briefing that Mr Putin’s visit to Tehran was in doubt because of the terror threat against him.

It never seemed likely that the Russian President would cut and run to Moscow after warnings that suicide bombers were conspiring to blow him up in Tehran.

Sure enough, Mr Putin calmly dismissed the threat at the press conference and insisted that he would leave for Tehran this evening. As he put it: “I would never leave home if I listened to all the various threats and the recommendations from the security service. They must do their job, while the Federal Chancellor, other colleagues and I must do ours.”

This was the only possible response, particularly from a leader whose image was formed by his tough suppression of Chechen separatists. But it begs the question why the Kremlin planted the doubt in a story of an alleged plot that remains shrouded in mystery.

Reaction in Russia seems curiously muted, given that it is a threat to assassinate a popular head of state within 48 hours. No information has emerged from Iran about any arrests, which raises serious questions about the President’s security if, as claimed, suicide bomb squads are roaming the streets of Tehran. Russian television stations were reporting that three groups of terrorists had combined to form a joint operation to kill Mr Putin.

Tehran has dismissed the plot as “psychological warfare” by Iran’s enemies to destabilise its relationship with Russia ahead of a crucial visit. Mr Putin is the first Kremlin leader to come to Iran since Joseph Stalin attended a summit with Winston Churchill and Franklin D. Roosevelt in 1943.

Certainly, the Iranian regime has much to lose from any terrorist attack against Mr Putin on its soil. Russia is standing out against pressure from the United States and Europe for tougher United Nations sanctions against Iran over President Mahmoud Ahmadinejad’s nuclear ambitions.

Sergei Lavrov, the Foreign Minister, warned only on Friday against “unilateral” measures to punish Iran either through more sanctions or military action. Russia is also completing construction of a nuclear reactor for Iran at Bushehr.

Chechen separatists were fingered by Russian special services as the organisers of two previous alleged assassination plots, in Ukraine and Azerbaijan, in revenge for Mr Putin’s war on the rebellious republic.

Chechnya’s population is largely Sunni Muslim, however, while Iran is Shia and hardly fertile territory for a fraternal conspiracy. Iran has shown little interest in expressing Islamic solidarity with Chechen rebels against Russia, not least because its confrontation with the West means that it needs good relations with Moscow.

Mr Putin marked his 55th birthday last weekend with approval ratings of 70 per cent, making him the envy of other G8 leaders. There seems no need to fabricate threats to rally the public to him, since voters would happily elect him to a third term if Russia's constitution permitted it.

There is an interesting historical echo from 1943. Stalin claimed to have uncovered a plot by the Nazis to assassinate Mr Roosevelt in Tehran, persuading the US President to stay at the Soviet Embassy during the summit. Perhaps somebody in the Kremlin wants to keep Mr Ahmadinejad equally close to hand, figuratively speaking, by underlining how isolated Iran would be internationally if it ever fell out of favour with Russia.

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