It was just a polite formality between two executives from rival outfits at a big annual conference. But the simple handshake between Iran's top diplomat and President Barack Obama is already a domestic political issue in the Islamic Republic.
Iran's foreign minister, Mohammad Javad Zarif, shook hands with Obama as national leaders gathered at the opening of the annual UN General Assembly session on Monday. The exchange of pleasantries was described as the first time in 30 years a US president extended his hand to a high-ranking Iranian official.
But as news of the handshake spread, hardliners in Iran immediately pounced. One lawmaker called the handshake "disgusting and unacceptable," and demanded that Zarif apologize to the Iranian nation.
Mansour Haghighatpour, a hardline lawmaker from the city of Ardabil, told the Fars News Agency that Zarif's handshake with Obama was an "obscene act," sending the message that Iran was ready to sit down have a "Nescafé" with its enemy. "This should only happen once America has apologized to the Iranian nation," he was quoted as saying.
Zarif, a US-educated Iranian diplomat, who served as his country's chief negotiator in the recent nuclear deal, downplayed the handshake. His people at the foreign ministry said their boss and Obama shared an unplanned, impromptu greeting in the hallways of the U.N.
They "ran into each other quite accidentally," an unnamed source close to the Iranian delegation at the UN told the official Islamic Republic News Agency.
Suggestions of "a pre-planned meeting are not right in any way," the official told IRNA.
The White House had a different take. A US official told CBS's Margaret Brennan the two shook hands at the luncheon for world leaders that U.N. Secretary-General Ban Ki-Moon held on Monday.
President Obama shook hands with Iranian Foreign Minister @JZarif yesterday at the luncheon, Senior Administration Official confirms.
Obama rang Iran's president Hassan Rouhani in 2013 after the moderate cleric just elected president visited the U.N. Rouhani also earned scorn from hardliners then for just taking the call.
Zarif regularly meets with Western officials and has repeatedly shaken hands with US Secretary of State John Kerry, his counterpart during nuclear negotiations.
Here's Zarif pressing the flesh with UK foreign minister Phillip Hammond during a meeting in Tehran in August.
And here's a shot of Rouhani shaking hands and exchanging pleasantries with French foreign minister Laurent Fabius in July.
So what's the big deal if Zarif shook hands with Obama?
Improving relations with the West, especially the US, will prove enormously popular among Iranians ahead of key February parliamentary elections Rouhani and Zarif's allies hope to win against more conservative factions.
Iran's hardliners are dreadfully worried a genuine rapprochement with the US would take away one of the original pillars of country's 1979 uprising, making a mockery of the chants of "Death to America," called out every Friday by regime adjutants at afternoon prayers in Tehran.
Backed by Iran's Supreme Leader Ali Khamenei, who appears to have welcomed the nuclear deal as a way to improve the Iranian economy but is wary of improving relations with the US, hardliners are eager to curtail any blossoming of the relations between the US and Iran.
The Supreme Leader last month even took to Twitter to make his point:
We waste no efforts to shut ways of infiltration into the country.We'll allow neither economic, nor political, nor cultural intrusion of US.