By Phil Stewart
WASHINGTON (Reuters) - The United States believes Iran's shadowy Quds Force is becoming increasingly aggressive overseas and may be working on other international plots beyond the alleged plan to kill Saudi Arabia's ambassador to Washington, three U.S. officials told Reuters.
U.S. allegations last week of a foiled plot in Washington have escalated tensions between the United States and Iran. They have also renewed Washington's focus on the Quds Force, the covert operations arm of Iran's powerful Islamic Revolutionary Guards Corps, which is believed to have sponsored attacks on U.S. targets in the Middle East -- but never before in the United States.
"They're being more aggressive ... not only in Iraq but worldwide," one senior U.S. official said in an interview. The official and others insisted on anonymity because they were not authorized to speak on the record and because of the sensitive nature of the matter.
U.S. officials have long charged that the Quds Force -- the Arabic word for Jerusalem -- has used proxies to attack U.S. troops in Iraq, Afghanistan and elsewhere.
The Quds Force, whose power within Iran is believed to be growing, is also active in Lebanon, the Gulf, Syria and elsewhere, officials said.
Many Iran specialists have reacted skeptically to the disclosure of an alleged Iranian plot within the United States itself. Tehran has dismissed the charges as a fabrication.
Some foreign nations briefed on the plot have raised questions. While President Barack Obama has so far demanded tougher sanctions on Iran and not a military reprisal, representatives of those nations are nonetheless wary, given the flawed intelligence case President George W. Bush made for war in Iraq.
Even U.S. officials now convinced of the plot's authenticity acknowledged they were initially doubtful due to the case's odd facts, including the bumbling nature of the Iranian-American now in custody, and his approach to a supposed Mexican drug cartel figure who happened to be a U.S. federal informant.
U.S. officials who spoke to Reuters declined to provide details of the evidence that the Quds Force may have other plots in the works. But two officials stressed they were based on more than just speculation or analysis.
"These are not merely aspirational plots dreamed up by the Quds Force. In fact, there is active planning around them," a second senior U.S. official told Reuters. Both senior officials played down concerns any attack was imminent.
A third U.S. official said the recklessness of the alleged attempt to assassinate Saudi Ambassador Adel al-Jubeir in Washington suggested that Quds "may be involved in other actions."
In the wake of the U.S. government's disclosure of the alleged plot, counterterrorism investigators in Britain are examining the possibility that other plots hatched in Iran were under way, a European government source said.
But the source said he and his colleagues were unaware of any current Iranian plots similar to the one the Americans said they had uncovered and disrupted.
IRAN'S 'SECOND MOST POWERFUL MAN'
U.S. officials said they believed Iran's Quds Force had expanded its power in recent years, exerting more control over the country's foreign policy.
Its commander, Qasem Suleimani, a brigadier general, has led the group's efforts to broaden Iran's influence in the Middle East, including by supporting Iraq factions that oppose the U.S. presence.
"His prominence within the Quds Force cannot be overstated. He is directly responsible for everything the Quds Force does," one U.S. military official, who is an expert on Iran, told Reuters on condition of anonymity.
Karim Sadjadpour, an associate at the Carnegie Endowment for International Peace in Washington, described Suleimani as "arguably the second most powerful man in Iran after the supreme leader," Ayatollah Ali Khamenei.
The United States has blamed Iran for an upswing in attacks against U.S. forces in Iraq over the summer that made June the deadliest month for U.S. personnel there since 2008. The United States also accuses Tehran of supplying weapons to Afghan militants, although on a far smaller scale than in Iraq.
In recent years, Suleimani's Quds Force has been "meddling in more places," the first senior U.S. official said.
"There are opportunities they think they can exploit in various places in the Middle East, that either they've got some foothold, and we're on one side, and they're on the other," the official said.
Vali Nasr, a professor of international politics at Tufts University, said the alleged plot cited by U.S. officials tracked with what appeared to be "far more aggressive Iranian behavior everywhere else."
He also cited Syria, Iraq, Lebanon, and Afghanistan.
"For some, it might be this news came in the context of a trendline that they were seeing with Iran," Nasr said.
U.S. officials have told Reuters they believe Suleimani is connected to the latest U.S. plot.
"Whether he is doing this like other things on his own or whether this is the direction of Khamenei, we can't say right now," the first U.S. official said. "It's a problem no matter what."
Nasr said he doubted the Quds Force would be doing something as risky as a plot on U.S. soil without political clearance from above.
Some Iran watchers were stunned that Tehran would choose to carry out an attack on U.S. soil, a potentially dangerous departure from past protocol. But U.S. officials following Iran told Reuters the behavior was consistent with the activities by the Quds Force and Suleimani.
"It makes a huge difference to us that it's on U.S. soil. But Iran has been, with only the thinnest of veils, seeking to kill U.S. troops and U.S. government individuals for years," the military official said.
(Additional reporting by Tabassum Zakaria in Washington and Mark Hosenball in London, Editing by Warren Strobel and Peter Cooney)