The failure of another high-profile attempt to persuade Iran to curb its nuclear programme in return for trade and diplomatic incentives leaves world powers with few options except to wait and hope that sanctions will eventually force Tehran to bend. But the Islamic republic shows no signs of blinking.
Iran's state-controlled media yesterday hailed Iranian negotiators for refusing to bow to "blackmail" and pressure from six world powers - the United States, Russia, China, Britain, France and Germany - at Friday and Saturday's talks in Istanbul.
Iran refused even to contemplate a confidence-building uranium exchange deal unless its international interlocutors first agreed to lift sanctions and accept Tehran's right to its own nuclear-fuel cycle. Tehran must have known these preconditions were unacceptable.
At the same time, the six world powers reportedly asked Iran to surrender a far larger percentage of its low-enriched uranium than they did 15 months ago. In turn, they must have known this was a nonstarter for Tehran.
No further meeting is scheduled, but both sides declared their readiness for more talks. Neither, however, appears to have mapped the way ahead, analysts said.
The one positive element is that the threat of a military showdown, which garnered so many alarming headlines last year, has receded.
The West claims that sanctions and cyber-sabotage have slowed Iran's uranium-enrichment programme. The outgoing head of Israel's Mossad intelligence agency, Meir Dagan, said this month that Iran would not be able to build a nuclear weapon before 2015.
The US secretary of state, Hillary Clinton, said on Wednesday the "very significant" new Israeli estimates allow breathing space to resolve the eight-year nuclear dispute with Iran.
But Iranian officials, defiantly, claim sanctions have made their country even stronger by encouraging the government to press ahead with much-needed economic reforms that reduce subsidies on fuel and food.
Iran's president, Mahmoud Ahmadinejad, yesterday shrugged off talk of failure of the discussions in Istanbul, arguing that Tehran never expected a breakthrough in a few preliminary meetings.
There could yet be progress and a "positive" outcome, he said, if international negotiators resisted pressure from some "uncultured Zionists" and the "bullying powers in Europe and the US".
Sir Richard Dalton, Britain's former ambassador to Iran, now a fellow at Chatham House, a leading British think tank, said: "We can now expect a stand-off for an unknown period … It's also unknown what extra pressure or isolation can be brought to bear on Tehran."
Britain's foreign secretary, William Hague, said Iran's "refusal to engage was "extremely disappointing".
Hardline Iranian media responded yesterday that Iran was a powerful regional and global player on an "equal footing" with western nations, which are purportedly soliciting Tehran's help to resolve their problems.
"The West needs Iran and that explains why they are desperate to sit for talks with the Islamic republic more often. But … the West has to pay a price for Iran's cooperation and assistance" in Iraq and Afghanistan, said the English language edition of the Tehran daily Kayhan.
Both sides, apparently believing time is on their side, underestimated the other's determination and misunderstood their intentions as they went into the Istanbul talks, experts say.
Iranian negotiators went to Turkey with the declared intention of shifting the focus from its nuclear programme to discussing wide-ranging "mutual concerns" of regional and global interest.
Tehran argued that earlier talks were a "one-way street" requiring it to make concessions without the other side "specifying its end game", said Farideh Farhi, a leading Iranian analyst based in Hawaii.
The six powers, however, were equally determined to keep the focus on Iran's uranium-enrichment programme, which the West suspects is aimed at developing weapons, a charge Tehran vehemently denies.
The US and other western powers had also declared that sanctions had begun to impact on Iran's calculations. "Obviously, they were wrong," Ms Farhi said in a telephone interview.
"Although the contours of an eventual compromise are there - allowing for some [Iranian] enrichment under a tightened inspection regime - the [two] sides seem unable or unwilling to… agree to a path that leads to that eventual compromise," Ms Farhi added.
The US is not expected to press for further sanctions against Iran at the UN Security Council, where it had difficulty persuading China and Russia to agree to a fourth set last summer. Washington is instead likely to push for stricter enforcement of existing penalties.
The diplomatic debacle in Istanbul, meanwhile, is unlikely to have endeared Iran to Turkey, which has good relations with Washington. Tehran clearly had hoped for progress that would have bolstered its status as a regional power. Turkey has stood up for Iran at the United Nations, risking US anger.
As the Istanbul talks began, Iran's envoy to the UN's nuclear watchdog, Ali Asghar Solantinieh, declared: "resolutions, threats, computer viruses nor even a military attack will stop uranium enrichment in Iran."