Iran-US relations: Sailors' detention highlights divisions
The video put out by Iran's Revolutionary Guard of the 10 American sailors in detention must have made difficult viewing in the United States. It was aired on the US networks just as Secretary of State John Kerry announced the men had been well treated.
The video showed the sailors kneeling on the decks of their boats with their hands on their heads, presumably at gunpoint, against the backdrop of triumphalist war movie style music.
In the video, the commander of the sailors is interviewed and apologises for straying into Iranian waters.
The timing couldn't have been worse - the sailors were detained just hours before President Barack Obama gave his State of the Union address to Congress.
The detention and subsequent release the following day of the sailors in the waters of the Persian Gulf served to show how much has changed following the nuclear agreement between Iran and six world powers last summer.
A direct channel of communication between the Mr Kerry and Iran's Foreign Minister Javad Zarif led to a quick resolution of the crisis between the two sides.
The two men were in constant touch to get the sailors released as quickly as possible. Their last phone call before the release of the sailors took place at 05:30 in the morning Tehran time.
The contrast couldn't be more stark with the last such incident. In March 2007, 15 British sailors were apprehended in what Iran said were its territorial waters.
It took 13 days before they were released amid a great fanfare by then President Mahmoud Ahmadinejad.
'Tense 40 minutes'
Although the British government maintained an ambassador in Tehran at that point, lines of communication were not as strong as today between Tehran and Washington.
The Iranians put the British sailors on planes back home, albeit in brand new suits, but refused to return their gunboats. This time the Americans sailed off in their vessels across the Gulf within 24 hours.
But the incident also shows that the nuclear agreement has done little to remove tension between Iran and the Unites States. It could easily get out of control and develop into a military confrontation.
Iranians have reported that there was a tense 40 minutes following the detention of the sailors and their transfer to the nearby Iranian island of Farsi. One revolutionary guard commander spoke of US jets flying very low over the island as a warning.
Hardliners in Iran are adamant that the nuclear agreement will not change things with the US.
While the timing of the incident this week might have been unfortunate for President Obama, it was just a few days before the United States and the European Union are due to lift crippling international sanctions against Iran as part of the nuclear agreement.
Heavy price paid
Iran is desperate to get its hands on its frozen assets - estimated to be in the tens of billions of dollars. The country could have risked jeopardising the lifting of the sanctions this weekend.
The sailors had to be released quickly in spite of the obvious reluctance of the Revolutionary Guard, whose naval units had captured the sailors and laid their weapons and equipment out for the cameras like the seized assets of terrorists or drug dealers.
The Revolutionary Guard find the nuclear agreement humiliating. The deal traded the lifting of sanctions for Iran's ability to reach the capability to build a bomb.
It has also robbed the Revolutionary Guard of the chance of having a nuclear option, should the need ever arise. President Hassan Rouhani has paid too heavy a price for the lifting of sanctions, they believe.
Crucially, the sailors would not have been released so quickly without the approval of Iran's Supreme Leader, Ayatollah Ali Khamenei. So far he has gone along with the nuclear agreement rather reluctantly.
He would not want his grip on power in a country deeply isolated and in dire economic straits to become tenuous. And just as the controversial nuclear deal was about to bear fruit for Iran, the Supreme Leader could hardly risk undoing it.
That of course won't stop hardliners spinning the event as a victory for Iran. Already the hardline newspaper Keyhan has a headline saying: "America tested us and we scared the hell of them!"
Q&A: Iran's nuclear deal
What is it? In July, Iran agreed a landmark nuclear deal with six world powers to limit its sensitive nuclear activities for more than a decade in return for the lifting of crippling sanctions. The US is confident the agreement will prevent Iran from obtaining a nuclear weapon. Iran says it has the right to nuclear energy - and stresses that its nuclear programme is for peaceful purposes only.
When is 'implementation day'? Iran will not see the UN, US and EU sanctions lifted until the global nuclear watchdog, the International Atomic Energy Agency (IAEA), certifies that it has fulfilled its commitments under the deal. Iran reportedly says the IAEA will do so this Friday. US Secretary of State John Kerry says implementation will take place "within coming days".
What does Iran stand to gain? The sanctions have cost Iran more than $160bn (£102bn) in oil revenue since 2012 alone. Once they are lifted, the country will be able to resume selling oil on international markets and using the global financial system for trade. Iran has the fourth largest oil reserves in the world and the energy industry is braced for lower prices. Iran will also be able to access more than $100bn in assets frozen overseas.