|The US had more than 5,000 troops in the Gulf as of September 30, according to the US Department of Defence
With tighter sanctions, talk of Iran shutting down the Strait of Hormuz and the assassination of yet another nuclear scientist in Iran, tensions are building on multiple fronts as a coalition of countries tries to stop Iran's nuclear programme.
Ali Larijani, Iran's parliamentary speaker, told the IRNA news agency on Thursday that UN nuclear inspectors would be welcome in the country and that issues with the nuclear programme can be resolved via negotiations. The path to diplomacy is, however, obscured by decades of ill will between Iran and the West.
The problems go as far back as the US and UK-led coup that unseated Prime Minister Mohammad Mossadeq in 1953 and reinstated the unpopular Shah. But even if historical baggage could be left in the past, today's issues alone are enough to pose major diplomatic stumbling blocks.
The Iranian government insists that its nuclear programme is peaceful and not aimed at weaponisation, while the US and some EU countries suspect otherwise. The West has upped the ante with harsh sanctions and embargoes since a November report from the International Atomic Energy Agency warned that it was "increasingly concerned" about the nature of Iran's nuclear programme.
As if to emphasise a point, Iran followed up talk of blocking the Strait of Hormuz with ten days of military exercises in the Gulf and an announcement that it has begun nuclear enrichment at one of its facilities.
"The Iranian threat has been blown out of proportion not because of Iran's impressive military might, but because people are unclear whether the Iranian regime is led by rational actors," said Karim Sadjadpour, an associate in the Middle East Programme at the Carnegie Endowment for International Peace.
He put things in perspective by adding that Iran's military budget is less than two per cent of that of the US, and less than a quarter of Saudi Arabia's.
But it's not just the West that is blowing things out of proportion.
"The Iranian government's paranoia is to some extent a self-fulfilling prophecy," said Sadjadpour.
The Islamic Republic of Iran has a solid history of tough talk, but it has escalated its provocative rhetoric in recent months. Sardar Mohamad Reza Naghdi, the commander of the Basij armed group, has said his organisation is "counting the moments" and waiting for an excuse to "put an end to the Zionist agenda".
|January 2012: Mostafa Ahmadi-Roshan, supervisor at Natanz Uranium Enrichment Facility, is killed by car bomb in Tehran. Iran blames Israel and US for the attack.
|July 2011: Darioush Rezai, a physicist and university lecturer, is shot in Tehran.
|November 2010: Two car bombs target two physicists, both reportedly involved in Iran's nuclear programme - Majid Shahriyari is killed while Fereydoun Abbasi-Davani is wounded. Iran blames Israel and the US.
|January 2010: Massoud Ali-Mohammadi, a nuclear scientist, is killed by a car bomb in Tehran. Anti-state activists say he was targeted because he supported opposition figure Mirhossein Mousavi, but the government only said the Tehran University lecturer did not work for its nuclear programme.
|June 2009: Shahram Amiri, a lecturer at Malek Ashtar University (closely connected to the Revolutionary Guard) said he was kidnapped in Saudi Arabia. He claims he was transferred to the US and enticed "to spread lies" about Iran's nuclear programme. The US denies this, claiming that Amiri was in the US of his own free will. Amiri returned to Iran in July 2010.
|February 2007: Although not a scientist, the disappearance of Ali Reza Asgari in Turkey was reported by the UK's Guardian to have been the result of a CIA plot targeting Iran's nuclear programme. Asgari, who some say was a US spy, had held a number of high-profile posts, including general of the Islamic Revolutionary Guard and a deputy cabinet minister of former President Mohammad Khatami.
In December, a high-altitude stealth reconnaissance drone was downed in Iran, and images of the drone were broadcast on Iranian TV with banners hanging off of its wings which read: "We'll crush America underfoot" and "US can't mess with us".
But Iran has been messed with. There was the Stuxnet computer virus, which in September 2010 attacked Iran's nuclear power plant in Bushehr.
There have also been several mysterious explosions at key locations in Iran. In October 2010, a blast at a military base in the western province of Lorestan killed "several" and was dubbed "an accident" by the government.
Another explosion in November killed 17 at an arms depot west of Tehran. Later that month, a blast was heard near the city of Isfahan, although the government denied that an explosion had happened, emergency services had initially confirmed it.
Although the US navy has twice in the past week rescued Iranian crews in Gulf waters - once from Somali pirates, once from a wrecked vessel - its presence in the Gulf is nonetheless unwelcome and seen as a threat by Tehran.
Strings of deaths, disappearances, and, in one case -reappearance - of Iranian physicists continues to deepen the acrimony and mistrust between Iran and the US and Israel.
Iran, for its part, retaliates mostly by arresting and charging foreigners with spying, as it most recently has with Amir Hekmati, a US-born Iranian. Hekmati, a former US marine, has become the first US citizen to be sentenced to death in Iran after being charged (in closed court) with espionage, corruption and being an enemy of God (mohareb).
Faraz Sanei, a researcher at the Middle East and North Africa division of Human Rights Watch, said Hekmati's case "may very well be politically motivated".
"By detaining Mr. Hekmati for months without providing him access to a lawyer or visits by his family and Swiss consular officials who represent American interests in Iran, Iranian authorities have deprived him of his fundamental right to be free from arbitrary arrest and detention, and to have access to a fair trial," Sanei said.
Surrounded by troops and weapons
Reza Marashi, research director of the National Iranian American Council, thinks two issues dominate the geopolitical map in the Middle East.
"One, you literally see Iran surrounded by US military bases - not just in Iraq and Afghanistan, but everywhere else. They are flanked by no less than 15, possibly 17 bases in the region ... so Iran's not unreasonable to have that threat perception," said Marashi.
"But more importantly, the United States and Iran have very different views on what the security architecture of the region should look like. Iran refuses to become a compliant US ally in the mold of Saudi Arabia, or Jordan, or Mubarak's Egypt. And the United States has an unfortunate track record of relations in the region - there's no example of a country that's on equal footing with the United States, right? And Iran refuses to enter into that relationship."
There are still troops and military contractors in Iraq and Afghanistan, and three US allies in the region - India, Pakistan and Israel - possess nuclear weapons.
Then there are the massive US weapons sales made to Iran's neighbouring countries - recent ones include $3.38bn worth of missiles to the UAE, $11bn in jets, tanks and more to Iraq and $30bn worth of hardware, including F-15 fighter jets, to Saudi Arabia.
The US-led wars in Afghanistan and Iraq have failed to deliver key strategic outcomes for Washington and have raised the stakes between the US and Iran because they "empowered the latter arguably at the expense of Washington", said Sabahat Khan, an analyst specialising in maritime security issues at the Institute for Near East and Gulf Military Analysis.
A divide as deep as the gulf
Tensions in the region have profound consequences for oil markets. Sadek Zibakalam, professor of politics at Tehran University told Al Jazeera's Inside Story the question isn't whether other countries can make up the gap Iran's oil should leave in the global market.
"The point is that the United States, by putting the embargo on Iranian oil is forcing the Islamic regime to take a drastic action, drastic decision, such as blocking the Strait of Hormuz."
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The sanctions, said Zibakalam, are tantamount to asking for regime change.
"If you prevent Iran from selling its oil on the international oil market, you are really saying that 'We are going to overthrow the Islamic regime.'"
And that, Sadjadpour told Al Jazeera, is Iran's primary concern - that "cultural and political subversion meant to inspire a 'velvet revolution' - something against which no nuclear weapon would guard.
Furthermore, Khan told Al Jazeera that Iran's perceptions of threats aren't just rooted in its poor relationship with Israel, but also in mistrust of the states in the Gulf Cooperation Council (GCC).
"Put crudely, Iran’s threat perceptions are defined by regional military competition, primarily with the United States, and a level of political competition with Saudi Arabia and the GCC."
Would nukes help Iran?
From the perspective of security, Khan said that "historically, nuclear weapons have been used defensively," as a deterrent from attacks, but that with a nuclear arsenal, Iran might become more aggressive, threaten the stability of the region and even prompt other countries, such as Saudi Arabia, to pursue nuclear weapons.
Also, in a way, the more foreign governments pressure Iran to back away from weapons via sanctions, the less chance they have of winning hearts and minds in Iran.
"More than anything else, what does help garner support for the Iranian government amongst the Iranian people is the sanctions and the secret assassinations and the killings that are going on," said Marashi. "Iranians are fiercely nationalistic and they're politically savvy and they're capable of thinking two thoughts simultaneously, meaning, 'We don't like it [that] our government beats, kills and imprisons us.'"
"'But we also don't like it when foreign countries do that to our nuclear scientists, we also don't like it when the United States says that the target of these sanctions is the government, not the people,' when ten out of ten times, it's the people who end up getting hurt the most, and it's the political elites who get to skirt the sanctions and continue to live lavishly."
Follow D. Parvaz on Twitter: @Dparvaz