While much of the world's attention focuses on Iran's nuclear program, Tehran has made considerable progress on another security front in recent years -- steadily increasing the reach and lethality of its naval forces. The goal by 2025, if all goes as the country has planned, is to have a navy that can deploy anywhere within a strategic triangle from the Strait of Hormuz to the Red Sea to the Strait of Malacca.

Should such plans materialize -- and Iran is making steady progress -- Tehran would redraw the strategic calculus of an already volatile region. The Persian Gulf is home to some of the world's most valuable supply lines, routes that are vital to the global energy supply. In the last few years, Iran has invested heavily in a domestic defense industry that now has the ability to produce large-scale warships, submarines, and missiles.

Since the end of the Iran-Iraq War in 1988, Iran has largely pursued a strategy of deterrence. Its ground forces, which number roughly 450,000, are trained and equipped to fight a prolonged, asymmetric defensive battle on its own territory. Likewise, Iran's air force can protect high value domestic targets such as the Natanz uranium enrichment facility and numerous military and political headquarters inside Tehran; it is incapable of long-range strike missions abroad. Iran simply does not possess the capability to project hard power into neighboring states.

But Iran's navy is different. It is the best organized, best trained, and best equipped service of the country's conventional military establishment. More than a nuclear weapons program, which would likely function as a passive deterrent, Iran's navy is an active component of Iran's activist foreign policy. The country's leadership, including Supreme Leader Ayatollah Ali Khamenei, has repeatedly said that Iran's navy is the critical foundation on which its long-term development and prosperity rests.

Iran actually has two navies -- the Islamic Republic of Iran Navy (IRIN) and the vaunted Iran Revolutionary Guard Corps Navy (IRGCN). The responsibilities of both have been expanding since 2007. The IRIN operates conventional surface and subsurface platforms and fulfills a more traditional naval role. It is now responsible for the Caspian Sea, the Gulf of Oman, and the blue waters outside the Persian Gulf. The IRGCN, which executes asymmetric operations with swarms of small boats that overwhelm the defenses of larger ships, has been tasked with defending the Persian Gulf and Strait of Hormuz. This reorganization reflects Tehran's desire to be a naval power that can deploy and operate well outside Persian Gulf waters (via the IRIN) while still retaining formidable coastal defenses in the Persian Gulf (via the IRGCN).

Evidence of Iran's growing naval assertiveness is already on display. In December 2010, Iran participated in a training exercise with Djibouti during a port call there. Tehran sailed away from that engagement with a partnership agreement that could allow Iran to use Djibouti as a logistical base supporting a larger and persistent Iranian presence in the Gulf of Aden and the Red Sea. Two months later, for the first time since 1979, Iran sent two ships through the Suez Canal to the Eastern Mediterranean, inducing the ire of both Israel and the United States. Neither country retaliated, but Israel closely tracked the ships as they sailed along the Israeli coast. This summer, Iran sent one of its Kilo class submarines to the Red Sea on a counter-piracy operation. Finally, Iran recently asserted plans to send naval patrols to the Western Atlantic. Although Iran probably doesn't have the capacity for such a mission, this kind of rhetoric speaks to Tehran's grand ambitions and is a way of emphasizing what it sees as the illegitimacy of the U.S. naval presence in the Persian Gulf.

On numerous occasions in recent years, IRGCN small boats have come dangerously close to U.S. and Western naval ships operating in the Persian Gulf. By all accounts, this is not an abnormal occurrence and usually ends with the small boat being turned away. But a recent change has increased the danger of escalation. Since 2005, Iran has been decentralizing command and control, not requiring subordinate commanders to get approval for all actions from senior leaders in Tehran. Thus, an IRGCN boat commander was able to take the initiative and capture a small crew of British sailors in 2007, a tactical action with strategic consequences. Should the IRGCN become more assertive, such engagements could spiral out of control.

Iran's emboldened navy is also increasing the country's influence throughout the region. The navy has the operational reach to visit countries that do not share a border with Iran. Such visits help foster good political relations, but, more important, they provide a foundation for military-to-military ties that can also yield operational benefits. For example, using ports in places such as Djibouti as resupply points allows Iran to increase the length and duration of deployments to waters outside its navy's traditional areas of operation. More worryingly, such an extended reach could also allow the IRIN to deliver weapons to various Iranian proxy groups abroad.

Moreover, the United States must now contend with the presence of IRIN ships well outside the Persian Gulf. This has enormous implications for U.S. military planners and commanders -- for example, it could force the U.S. Navy to implement increased force protection measures in waters, such as the Red Sea, that were once considered less volatile. Iran could soon have the ability to deny the U.S. entry through the Strait of Hormuz and into the Persian Gulf.

In many ways, the origins of Iran's naval buildup stem from embargoes that the U.S. slapped on Tehran during its war with Iraq, more than two decades ago. Since then, Tehran has sought what it calls "self-sufficiency." It has invested heavily in a domestic defense industrial base. Employing Chinese, Russian, and North Korean technology, Iran has begun building its own ships, submarines, and missiles.

That industry is now producing. In 2010, the IRIN put its first domestically manufactured traditional surface combatant, the Mowj class destroyer, to sea. Tehran has also built four Combattante II class guided missile patrol boats. In August 2010, it expanded the Peykaap/Tir class line, a fast-attack craft capable of carrying anti-ship cruise missiles and hitting a cruising speed of 55 knots. The U.S. Office of Naval Intelligence says that these programs "demonstrate Iran's ability to produce mid- to large-size ships" and "will likely be followed by others."

Iran is also producing its own submarines and missiles. It has added multiple Ghadir class mini-subs to its order of battle since the reorganization. In 2007, Iran had only three in service. Now it has eleven, with another nine expected in the next three years. In 2008 Tehran announced the opening of a production line for a larger, more potent submarine platform, the 1,000 ton Qa'em class. It is working on its own missile designs, too, by reverse-engineering older Chinese models. The IRGCN test fired one such missile last spring, claiming an effective range of 186 miles. Last month, Tehran announced that it had begun full production of one based on those tests.

Reaction to the buildup in the Gulf has been mixed. For most of the six states that make up the Gulf Cooperation Council, Iran's nuclear program remains the dominant regional security concern. With the United States' Fifth Fleet stationed in Bahrain and serving as the prime guarantor of maritime security across the region, the GCC has displayed little angst over Iran's growing naval power. Saudi Arabia, however, has been taking Tehran's growing assertiveness seriously. According to news reports, Riyadh is looking to spend another $30 billion to upgrade the Royal Saudi Navy (on top of the $60 billion arms deal that Washington and Riyadh signed in 2010). Final word on the new agreement could be announced by the end of the year.

Washington, meanwhile, has responded in a few different ways. Then Chairman of the Joint Chiefs of Staff Admiral Mike Mullen suggested last month that Tehran and Washington link up a hotline to avoid miscommunication and prevent accidental tactical naval engagements from spiraling out of control. Tehran rejected the idea, presumably because it would give legitimacy to an ongoing U.S. naval presence in the Persian Gulf. Asked about Iran's September announcement that it would deploy naval vessels to the U.S. Atlantic coast, White House spokesman Jay Carney dismissed the possibility, saying that the White House did not take such pronouncements seriously.

Iran will obviously never reach naval parity with the United States, but the GCC countries, even with their newer, Western-supplied ships, would likely find themselves on the losing end of a naval engagement with Iran, mainly because of their minimal force numbers and their inability to coordinate any naval campaign. As long as the United States continues to provide maritime security in the Middle East, the GCC will be able to rest easy. But Iran has a head start and the GCC should start thinking about implementing a naval modernization and development plan of its own.