The alleged Iranian plot against the Saudi ambassador to Washington was "amateur hour," an unusually clumsy operation for Iran's elite foreign action unit, the Quds Force, U.S. officials said Wednesday as further stranger-than-fiction details emerged of the assassination gone wrong.

The Iranians' would-be covert operative turned to a woman he met while working as a used car dealer, hoping to find a Mexican drug dealer-assassin, and wound up with an American informant instead, according to two U.S. law enforcement officials.

Other U.S. officials said Manssor Arbabsiar made further mistakes, including arranging a pay-off for the attack in an easily traceable way.

They attributed the missteps to Iran's relative inexperience carrying out covert operations in the United States and Mexico.

They said the U.S. believes the planned attack on the Saudi ambassador was conceived in part as proof that such an operation could be carried off. Then, perhaps, Iran would have followed up with a series of attacks against other embassies in the U.S. and in Argentina, officials said.

All of the officials requested anonymity in order to provide details from classified analyses and an active criminal case.

In public remarks, Secretary of State Hillary Rodham Clinton spoke Wednesday of a "dangerous escalation" of what the U.S. claims is an Iranian pattern of franchising terror abroad.

"We will work closely with our international partners to increase Iran's isolation and the pressure on its government and we call upon other nations to join us in condemning this threat to international peace and security," Clinton said at a Washington conference.

Her words strongly suggested that the U.S. wants some new action against Iran from the U.N. Security Council, which has already approved several rounds of mild to moderate sanctions on Iran over its disputed nuclear program.

Two men, including a member of Iran's Quds Force special foreign actions unit, were charged in New York federal court Tuesday with conspiring to kill the Saudi diplomat, Adel Al-Jubeir. Justice Department officials say the men tried to hire a purported member of a Mexican drug cartel to carry out the assassination with a bomb attack while Al-Jubeir dined at his favorite restaurant.

U.S. officials believe Iran hoped that an attack of that design would be blamed on al-Qaida. That, in turn, would strike at two of Iran's chief enemies: the U.S., constantly at odds with Iran over its nuclear aspirations, and Saudi Arabia, battling Iran in a diplomatic Cold War for influence across the Persian Gulf and Middle East.

Saudi Arabia most recently helped thwarted Shi'ite-minority demonstrations in Bahrain whom Iran backed, and clashed again with Iran in Syria. Iran advised Syrian leaders on how to crack down on demonstrators, while Saudi Arabia has encouraged further protests and called for the Syrian government's ouster.

The Quds Force is tasked with extending Iranian influence through fear and violence, intimidating other countries with assassinations, terror attacks and kidnapping, the officials said.

Such plots are managed by the Quds Force's Special External Operations Unit, and carried out by sometimes unexpected proxies, like anti-Shiite Sunni extremists, the officials said.

The unit answers directly to Iran's supreme leader, Ayatollah Ali Khamenei, who U.S. officials believe is briefed on high-profile operations. While the U.S. has no direct proof, and did not charge in court, that the top Iranian leaders approved this attack, any such operation would be vetted at the highest levels, one of the officials said.

U.S. law enforcement officials said the criminal charges were limited to those actions they could prove in court, and did not cover all the information they had gathered about possible Quds Force goals or intentions. Even the roles of three of four Quds officers connected to this plot were not detailed in the criminal case but instead were laid out in economic sanctions imposed on them administratively by the Treasury.

During an interview with The Associated Press, Clinton said the Obama administration is stepping cautiously and won't overstate its case.

The alleged plot "does give a lot of credibility to the concerns" about other Iranian activity, Clinton said in the interview Tuesday. "But we have to be careful, and we've tried to be very careful in this instance. What you'll see in the complaint is what we know, what we can prove."

The U.S. blames the Quds Force for some of the worst terrorist acts against U.S. troops overseas, including the 1996 Khobar Towers bombing that killed 19 Americans in Saudi Arabia.

More recently, the group has smuggled long-range rockets into Iraq for use by Shiite militant groups, including in an attack on Camp Victory outside Baghdad on June 6, that killed six U.S. servicemen, U.S. officials said.

The Iranian group also plays a double game in Afghanistan, providing overt cash and economic aid to the Afghan president while funneling weapons such as long-range rockets to the Taliban, the officials said.

Arbabsiar is a 56-year-old naturalized U.S. citizen who also had an Iranian passport. In May 2011, the criminal complaint says, he approached someone he believed to be a member of the vicious Mexican narco-terror group, Los Zetas, for help with an attack on a Saudi embassy.

The man he approached turned out to be an informant for U.S. drug agents, who in return for leniency on drug charges against him had become a paid informant and had led U.S. agents to several drug seizures, according to the criminal complaint filed in federal court in New York.

Arbabsiar was introduced to the informant by a woman he had met when he previously worked as a used car salesman in Corpus Christi, Texas, two law enforcement officials said. She was the informant's aunt.

The informant was not actually a member of Los Zetas but had worked with drug traffickers and was able to present himself as a Zeta to Arbabsiar.

A more savvy operative might have been suspicious when the informant set up meetings in Reynosa, Mexico, the territory of a rival gang where a Zeta would not be welcome.

The government charged that Arbabsiar had been told by his cousin Abdul Reza Shahlai, a high-ranking member of the Quds Force, to recruit a drug trafficker because drug gangs have a reputation for assassinations. The Zetas are known for the brutality of the beheadings, mass killings and grotesque mutilation of their victims.

As the covertly recorded meetings between Arbabsiar and the informant continued, the plot eventually centered on targeting Al-Jubeir in his favorite restaurant, though the informant didn't name any specific restaurant, officials said.

There was also discussion between the two of possibly bombing other targets later, possibly including the Saudi and Israeli embassies in Argentina and the Israeli Embassy in Washington, two law enforcement officials said. But they emphasized that no plans were devised for such attacks, one reason this was not included in the criminal charge.

When the Iranian agent transferred more than $100,000 in two batches to the informant, U.S. authorities decided to act, senior U.S. officials said.

In addition to Arbabsiar, the criminal complaint named Gholam Shakuri, described as Shahlai's deputy in the Quds Force who helped provide funding. Shahlai was identified by the Treasury Department in 2008, during George W. Bush's administration, as a Quds deputy commander who planned a Jan. 20, 2007, attack in Karbala, Iraq, that killed five American soldiers and wounded three others.

Arbabsiar, Shakuri and Shahlai and two others — Qasem Soleimani, a Quds commander who allegedly oversaw the plot, and Hamed Abdollahi, a senior Quds officer who helped coordinate — were put under economic sanctions Tuesday by the Treasury for their alleged involvement. The department described all except Arbabsiar as Quds officers.


Associated Press writers Alicia Caldwell, Matthew Lee, Pete Yost, and Nedra Pickler contributed to this story.

AP Intelligence Writer Kimberly Dozier can be followed on Twitter via (at)kimberlydozier