Ahead of the military maneuvers, Supreme Leader Ayatollah Ali Khamenei accused Washington of trying to dominate the world through its nuclear arsenal and vowed that Iran would not bend before what he called “implicit atomic threats.”
Khamenei was referring to Obama's announcement earlier this month of a new nuclear strategy that focuses less on Cold War threats and more on preventing the spread of weapons. As part of the new guidelines, Washington vowed not to use its arsenal against nations that don't have their own nuclear weapons, with the exception of countries that are not abiding by international non-proliferation rules - a caveat the administration said meant Iran and North Korea.
Khamenei's rhetoric, depicting Washington as seeking to dominate Iran, appeared aimed at keeping up support at home as Iran tried to fend off a new US attempt to win a fourth round of United Nations sanctions over Iran's nuclear program.
The Obama administration is lobbying hard at the UN Security Council for tougher punishment of Iran over its refusal to suspend uranium enrichment, a process that can produce either a warhead or fuel for a nuclear reactor. The US and its allies accuse Iran of seeking to build a weapon, a claim Tehran denies.
Tehran launched its own push Thursday to try to weaken the US sanctions campaign as Foreign Minister Manouchehr Mottaki headed to Austria, the first of several Security Council members he plans to tour in coming days. Mottaki has said he wants to talk with council members about possibilities for a nuclear fuel deal that was originally touted as a possible way to ease the international standoff over Iran's nuclear program but has since hit a dead end.
Iran has been holding military maneuvers, dubbed as The Great Prophet, in the strategic waters of the Persian Gulf annually since 2006 to show off its military capabilities - and serve as an implicit warning of the consequences if the United States or Israel attack Iran's nuclear facilities.
Iran's leaders have said in the past that if attacked, the country would respond by shutting off the Strait of Hormuz, the mouth of the Gulf through which around 40 percent of the world's oil and gas supplies pass, as well as by attacking American bases in the Gulf.
In 1988, the US Navy accidentally shot down an Iranian civilian airliner over the waterway as the eight-year Iran-Iraq war was winding down and killed nearly 300 people. Iran claimed it was intentional, as a show of support to Iraqis. The US later paid compensations for the victims.
The three-day war games brought in naval, air and ground units from the Revolutionary Guard, state television reported. In the past four years, the maneuvers were held in the summer, and there was no official explanation why they were brought forward this year. But it came after repeated denunciations by Iran's top leaders over the past week of the new US nuclear policy.
On Thursday, the military unveiled a new attack speedboat, describing it as an “ultra-speed and smart” vessel called “Ya Mahdi.” Iran also said 313 smaller speedboats with the capability of firing rockets and missiles would participate.
State television later showed video footage of a Ya Mahdi vessel firing rockets at a still target in the sea, while dozens of the small speedboats launched rocket-propelled grenades at an abandoned ship and troops boarded it in a simulated attack on an enemy warship.
On Wednesday, Defense Minister Gen. Ahmad Vahidi said “new weapons” would be test-fired in the war games, but did not give details. Iran has declared many advances in its military industries and sciences to demonstrate self-sufficiency despite sanctions and attempts by the US and its allies to isolate the country.
The annual maneuvers are also a testimony to the growing power in Iran of the Revolutionary Guard, the elite force tasked with protecting the rule of Islamic clerics. The 120,000-member force is separate from the regular military, with its own naval, air and ground forces, and has grown to take a hand in every critical area including missile development, oil resources, dam building, road construction, telecommunications and nuclear technology. It also has taken the lead in cracking down on Iran's domestic opposition amid the turmoil since last year's disputed presidential election.
US officials played down the significance of the war games.
Pentagon press secretary Geoff Morrell said “they don't seem out of the ordinary” from what Iran's military has done in the past. He also said Tehran often makes exaggerated claims about its weapons testing.
The US Navy said its expected “no significant impacts” to its operations in the area, where it has a number of ships, including the aircraft carrier USS Eisenhower.
On Wednesday, ahead of the exercises, Khamenei spoke to a conference of nurses and denounced Obama's new nuclear guidelines. US officials have said the changes aim to push Iran into cooperating with the UN on its nuclear program, but the supreme leader depicted them as dangling the threat of nuclear attack over his country.
“Implicit atomic threats against Iran will have no effect,” he said. “The Iranian people will not submit to such threats and will bring those who make them to their knees.” He repeated that Iran is not seeking to build a nuclear weapon.
“The nuclear powers, particularly the United States, are using their nuclear might to try to impose their authority over the world,” he said.
Iranian President Mahmoud Ahmadinejad, meanwhile, flew to Zimbabwe on Thursday where he was welcomed by President Robert Mugabe - a meeting of two leaders united in fierce opposition to the West Iran is the biggest exhibitor at a trade exposition Ahmadinejad is scheduled to open in Zimbabwe's second city of Bulawayo on Friday.