U.S. officials increasingly say they suspect that Maj. Gen. Qassem Suleimani, Iran's covert action mastermind, is operating in Syria, helping Tehran's key Arab ally, President Bashar al-Assad, crush a stubborn 10-month-old uprising against his rule.

If these suspicions are correct, this would be a key mission for the shadowy Suleimani, who specializes in using covert pressure to secure strategic objectives.

There have been unconfirmed reports that Suleimani was in Damascus this month as the crisis in Syria seemed to be moving from a popular uprising toward civil war between the minority Alawite regime and the Syria's Sunni majority.

Tehran has a lot at stake here.

Some Middle East analysts say that if Assad was overthrown and Iran lost its gateway to the Levant and its prize proxy, Hezbollah, Tehran could be forced to rethink its strategy in its confrontation with the West in the Persian Gulf.

But there are signs that Suleimani, commander of the al-Quds Force, covert operations arm of Iran's powerful Islamic Revolutionary Guards Corps, is fast becoming a major player within the Tehran regime.

That could signal a strengthening of conservative hard-liners in the current power struggle within the regime, which could impact on the current standoff in the oil-rich gulf.

There are suspicions, too, that Suleimani's entry into the potentially explosive crisis in Syria will affect the wider Levant region, including volatile Lebanon, where Syrian dissidents are being sought.

Syria's -- and Iran's -- key ally in Lebanon is Hezbollah, the Shiite Muslim organization that Western intelligence officials say is actively helping Assad's regime fight its foes.

Many of Lebanon's Sunnis, led by former Prime Minister Saad Hariri, is confronting the Hezbollah-dominated government in Beirut, fostering fears of a Sunni-Shiite conflict in a nation plagued by sectarian rivalries.

Four members of Hezbollah, including two senior figures, have been indicted for the Feb. 14, 2005, assassination of Hariri's father, Rafik, five times prime minister of Lebanon, by a U.N.-mandated special tribunal in the Netherlands.

Hezbollah denies involvement in the Hariri killing, in which Syria was long seen as the main suspect.

For Suleimani, who spent several years causing mayhem for the Americans in Iraq before they withdrew their forces in December, this cauldron of intrigue and murder is the kind of death-and-diplomacy mission of which he is seen as a master.

Indeed, Suleimani, who spent many years operating in the shadows, is taking a more openly influential role in Tehran's expansionist policies that suggest his personal power within the fundamentalist regime is growing.

In Iran, the power of the Revolutionary Guards, the al-Quds Force's parent organization, appears to be growing by the day.

It's increasingly seen as supporting Iran's ultra-conservative supreme leader, Ayatollah Ali Khamenei, in his power struggle with the politically ambitious President Mahmoud Ahmadinejad. Suleimani answers directly to Khamenei.

Reflecting his growing status in Iran's ruling elite, Suleimani last month stepped into the limelight and openly declared that Iraq and Hezbollah-dominated South Lebanon, on the Israeli border, were effectively under Iranian control.

Everyone's known that for years but Suleimani was the first Iranian leader to boldly declare it up front.

That caused immense consternation among Hezbollah's Christian and Sunni adversaries. But they've shown little inclination to take on Hezbollah and its powerful military machine, even while it's distracted helping Assad.

Amal al-Hazzani of King Saud University in Riyadh, where Iran is deemed Saudi Arabia's primary enemy, observed that Iraq's political leaders are also powerless to defy Iran.

"Iraq's Sunni politicians … feel that Suleimani in particular still harbors the belief that the Iraq-Iran war of the 1980s has only just ended with Iran being victorious, and that he's among the prominent leaders of this victory," Hazzani noted.

"As for Prime Minister Nouri al-Maliki, he willingly submits to the Iranian domination that brought him to power, a domination which is in fact his only way to survive …

"If Suleimani succeeds as planned in delaying the Syrian regime's downfall, such a success … would be an indicator of the rise of Suleimani at the expense of President Ahmadinejad."

If the gulf crisis erupts into conflict, Suleimani would be the man who unleashes Iran's retaliation against the West and its Arab allies like Saudi Arabia through proxies like Hezbollah -- terrorist attacks, assassinations, kidnappings and sabotage.