But the deployment, announced Saturday in Tehran, could bring closer the prospect of a confrontation with Saudi Arabia, its regional rival, amid rising tension in the Gulf and Red Sea regions, both vital oil arteries.
The Iranian move coincides with a Saudi naval blockade in the Red Sea to intercept arms shipments allegedly sent by Iran and Eritrea to Shiite rebels fighting Saudi forces in northern Yemen.
The Yemeni government of President Ali Abdullah Saleh claims the Iranians are arming the Zaidi Shiite rebels who have fought Saleh's forces to a standstill in three months of combat in the mountains of Saada province along the border with Saudi Arabia. Yemen is predominantly Sunni Muslim.
The rebellion began in 2004 but intensified sharply in August, when Saleh launched an all-out offensive dubbed Operation Scorched Earth against the tribesmen.
Two weeks ago the Saudis, in a rare use of Riyadh's military power, joined forces with Saleh's army to fight the rebels after they crossed the 930-mile frontier and killed a Saudi officer.
Since then the Saudis, who see themselves as the guardians of Sunni Islam, have mounted repeated airstrikes against the rebels.
Riyadh also sent ground forces into Saada province to establish a 7-mile-deep cordon sanitaire inside Yemeni territory.
The territorial intrusion was apparently condoned by Saleh's beleaguered regime. It is also grappling with an increasingly violent separatist movement in south Yemen, a socialist state before union with the north in 1990, a resurgent al-Qaida and a collapsing economy that is causing unrest.
The Saudis, who do not want to see Yemen collapse into chaos that al-Qaida could exploit to menace the kingdom, dispatched three warships with marine commandos from its Red Sea base at Yanbu last Thursday to patrol off northern Yemen.
The Sanaa regime claimed its navy intercepted an Iranian-crewed ship laden with weapons in the Red Sea on Oct. 26. Tehran denies it is aiding the rebels.
However, Texas-based security consultancy Stratfor reports that Tehran has also been ferrying veteran fighters from Lebanon's Iranian-backed Shiite Hezbollah movement to Yemen to bolster the insurgents, known as Houthis after the clan that leads them.
The objective of the Saudi blockade is to interdict the alleged Iranian arms route via Eritrea, on the western shore of the Red Sea.
Relations between Eritrea and Yemen have been strained for some time, and border clashes were reported throughout the 1990s.
The regime in Asmara, Eritrea's capital, is one of the most secretive in Africa and is accused by its neighbors of aiding Islamist militants fighting in Somalia.
Stratfor says that since the Saudi blockade began, the Iranians are now using a longer route that starts at Asab, a port in southeastern Eritrea, to move the weapons.
The route curls eastward around the southern tip of the Arabian peninsula into the Gulf of Aden, where Iranian naval vessels are now deploying, to Shaqra on Yemen's southern coast.
From there, Stratfor maintains, the arms are moved north overland to Marib in central Yemen, and then on to the Saada mountains. If that is the case, the Saudis are likely to deploy their own warships in the Gulf of Aden.
Stratfor reported Monday that "Iran appears to be using the naval assets (in the Gulf of Aden) to protect its supply lines to the Houthi rebels …
"It is not yet clear how aggressive Saudi and Iranian rules of engagement are, or how close they are to coming into conflict with one another.
"But with Iranian warships apparently facilitating the smuggling of arms that Riyadh is intent on interdicting, the potential for an incident or conflict at sea is certainly on the rise."
As the proxy war between the two Gulf powers appeared to escalate, Iran's army commander, Maj. Gen. Hassan Firouzabadi, warned Tuesday that Saudi "Wahhabi state terrorism" in Yemen could have consequences across the region.
The official Saudi Press Agency reported that King Abdullah met with U.S. Director of Central Intelligence Leon Panetta in Riyadh Sunday.
In Washington, U.S. Defense Secretary Robert Gates met with Saudi Arabia's visiting deputy defense minister, Prince Khaled bin Sultan, Tuesday to discuss "regional security issues."
