DUBAI, United Arab Emirates – In the span of just a few hours, announcements bouncing between Tehran and Washington showed the direction of their showdown: New issues are piling up even as Western envoys try to find a path to move nuclear talks forward.
In quick succession last week: Iran said it seeks to build a nuclear-powered submarine, the U.S. unveiled more sanctions and a senior Iranian military official ramped up denunciations of Middle East nations trying to topple the Tehran-allied regime in Syria.
The developments taken individually reflect significant trends, including Iran's split personality between portraying itself as a rising military power while growing insecure about losing critical regional influence if President Bashar Assad falls in Damascus. But seen as a whole, the moves underscore the hardening positions that could hamper next week's attempt to regain diplomatic traction on negotiations over Iran's nuclear ambitions.
"There is a lot of background noise with the nuclear talks," said Sami al-Faraj, director of the Kuwait Center for Strategic Studies. "It seems to be getting louder."
For the moment, there is no date to resume talks between Iran and world powers following the last month's session in Moscow. That could depend on the outcome of discussions next Tuesday between Iran's No. 2 negotiator and the top deputy for the European Union's foreign policy chief, Catherine Ashton.
At the heart of the talks is how much the West is willing to allow Iran to enrich uranium, which at low levels creates fuel to power reactors but can be boosted to weapons grade material. Iran insists it will never surrender its ability to make nuclear fuel, but says it seeks reactors only for energy and medical applications.
Iran's declared pursuit of a nuclear sub -- although in the early stages and still possibly out of reach of Iranian engineers -- is now a potential deal-breaker in the haggling over enrichment.
Submarines need nuclear fuel enriched well beyond the 20 percent level that marks Iran's highest acknowledged output. The issue could open demands by Iran to push production much closer to warhead levels at 95 percent enrichment -- which is certain to stir calls in Israel and elsewhere to abandon dialogue and look to possible military action.
Israeli Prime Minister Benjamin Netanyahu blamed Iran for a deadly blast Wednesday on a bus filled with Israel tourists in Bulgaria, and promised a tough response.
The proposed sub is part of Iran's strong emphasis in recent years on boosting naval power. Iran seeks to offset the expanding U.S. Navy presence in the Gulf and project its own military presence farther afield by sending warships into the Mediterranean and Indian Ocean.
Iranian commanders this week renewed threats to block the Strait of Hormuz at the mouth of the Gulf -- the route for one-fifth of the world's oil -- in response to tighter Western sanctions. But there has been no evidence of Iranian ships challenging tankers.
The Pentagon, meanwhile, is boosting its naval forces in the region. The aircraft carrier USS John C. Stennis is now on an accelerated timetable to return by late summer to ensure that two carriers are in the area. Another ship, the USS Ponce, has also been deployed to the Gulf as a floating base for attack forces.
Iran has responded with volleys of tough talk possibly tailored to counter domestic grumbling about the country's increasing isolation.
"The U.S. aircraft carriers are nothing more than scrap iron for the Revolutionary Guard," said the corps' deputy commander, Hossein Salami. "The Guard doesn't fear the greatness of the U.S. aircraft carriers."
On Monday, the conservative Iranian website Mashreghnews.ir said the country will one day need to churn out enrichment at "50 to 60 percent" for a future nuclear-powered fleet.
"Iran won't give up its nuclear rights," said a hardline Iranian parliament member, Mohammed Esmaeili. "At the same time, it won't shun talks. It will continue negotiations."
And the West will likely keep applying pinpoint sanctions to try to gain more leverage. British Foreign Secretary William Hague said Tuesday that sanctions would "intensify" in the coming months if there is no progress in the talks.
In a rare official acknowledgment of the economic bite, Iran's parliament speaker Ali Larijani was quoted Tuesday as saying that sanctions were to blame for 20 percent of the country's economic problems.
The main blows have been against Iran's critical oil exports, including a boycott by the 27-nation EU that took effect July 1. The targets of the latest U.S. sanctions included 11 companies the Treasury Department claims have links to Iran's defense ministry, the Revolutionary Guard and other state-backed institutions.
"The economy is a far more immediate and existential issue for the regime" than internal political opposition, said Meir Javedanfar, an Iranian-born political analyst based in Israel.
He speculated that Iran's Supreme Leader Ayatollah Ali Khamenei may want to keep nuclear negotiations on track in fear that escalating tensions with the West would "worsen his regime's economic woes."
There's also the uncertainties over Syria and whether Iran may one day face a post-Assad leadership indebted to Iran's Gulf Arab rivals, such as Saudi Arabia, which have become leading backers of the Syrian rebels.
On Wednesday, a bomb ripped through a high-level security meeting in Damascus, killing three top regime officials in the harshest blow to Syria's ruling family dynasty and the rebels' boldest attack in the country's civil war.
The war has pried open rifts among Iranian officials about the wisdom of sticking by Assad amid mounting international outrage at the bloodshed. Some diplomats have been quoted as questioning Iran's continued backing for a Syrian regime that could face war crimes accusations in the future.
Others have pushed back harder against Assad's opponents.
"It is the duty of Syria's Muslim neighbors to refrain from backing the `terrorists,"' Iran's armed forces chief of staff, Gen. Hassan Firouzabadi, was quoted as saying in a message to Turkey and Jordan to block rebel movements.
The West has tried to keep regional issues out of the nuclear talks agenda, but the pressures are certain to shape Iran's strategies if the negotiations move forward, experts say.
Iran "had to weather quite a lot in the past," said Mouin Rabbani, a Jordan-based contributing editor to the journal Middle East Report. "It's used to playing an increasing small number of cards to their maximum advantage."