The arrest of two Iranians suspected of attempting to carry out a vehicle bombing in Iraq on Monday focused new attention on how Tehran is trying to protect its interests in the country it fought for eight years in a devastating war.

So far, Iran is believed to have used money, not guns, to influence Iraq — particularly by spreading wealth among Shiite political factions — while avoiding a direct confrontation with its longtime rival the United States.

Monday's arrests came on the heels of comments by Iraqi Foreign Minister Hoshyar Zebari (search) saying some neighboring countries were financing and training terrorists in Iraq, apparently referring to Iran and Syria.

Syrian President Bashar Assad (search), at the end of a two-day trip to Iran on Monday, said developments in Iraq are "the most important issue" for Syria and other neighbors of Iraq, including Iran.

Iran's powerful former President Hashemi Rafsanjani (search) said Syria, Iran and Turkey should coordinate their policies to prevent the disintegration of Iraq, the Islamic Republic News Agency reported on Monday.

The "conspiracies" being hatched by "Washington and Tel Aviv" against Iraq call for increased "strategic cooperation" between Iran and Syria, Rafsanjani was quoted as saying.

The announcement of the arrests by the Iraqi Interior Ministry was a rare instance tying Iranians to a particular attack.

But there was no indication that the two men — who the ministry said were caught trying to detonate a car bomb in an eastern Baghdad neighborhood Monday — were Iranian government agents. They might instead be working on their own.

Iranians enraged that Shiite shrines in Iraq were damaged in fighting between U.S. troops and Iraqi insurgents have volunteered to join the battle against the Americans.

Iranian officials have said they would try to stop zealots from crossing the border — and Iran's supreme leader, Ayatollah Ali Khamenei (search), has refused to give a green light to one group, the Devotees for Martyrdom, that says it's eager to fight in Iraq.

Tehran insists it has no interest in fomenting instability in its neighbor to the west — and many observers say that a smooth path to elections could benefit mostly Shiite Iran, since a vote will likely bring an Iraqi government dominated by Shiites.

Foreign Ministry spokesman Hamid Reza Asefi told reporters Sunday that Tehran wants only "stability and security in Iraq."

"We haven't done any action that may smell of an act of interference in Iraq's internal affairs from the very beginning, and won't do so in the future either," Asefi said.

Tehran fears the United States is cementing its influence in Iraq. But at the same time, Iran can little afford an open clash with the Americans — something that backing for anti-U.S. violence would likely bring about.

To date, Iran has not been considered a source of manpower or financing for Iraq's mainly Sunni Muslim insurgency, said a Western diplomat in Baghdad who spoke on condition of anonymity.

Instead, it is believed to be involved in intelligence gathering inside Iraq, while quietly funding Shiite political parties in a bid to influence the government that emerges from January's elections, the diplomat said.

"Iran wants to be a silent power broker," said Iranian political analyst Davoud Hermidas Bavand. "And Iran needs to make sure that the government in Iraq will not be America's puppet."

The United States, which has been at odds with Iran since the pro-U.S. shah was toppled in the 1979 Islamic revolution, fears Iran wants to establish a fundamentalist Shiite regime in its own image in Iraq.

Saddam brutally suppressed Iraq's Shiites and fought a devastating war with Iraq from 1980-88 that is thought to have killed a million people from the two sides.

Since Saddam's fall, Washington has repeatedly accused Tehran of sending money to various Iraqi groups, dispatching intelligence agents and allowing foreign anti-American fighters to travel to Iraq through its territory. Iran has persistently denied the charges.

Iranians have been detained previously in Iraq — U.S. records show several people listed as born in Iran as currently in American custody — but none has been publicly accused of involvement in violence.

Members of Devotees for Martyrdom (search), a loose grouping of Iranian religious extremists, have said they will go to Iraq as soon as Khamenei gives them the go-ahead.

But Khamenei did nothing when Iranian officials barred volunteers from entering Iraq earlier this year when fighting between U.S.-led coalition forces and militiamen loyal to Muqtada al-Sadr (search) damaged Shiite shrines.

Grand Ayatollah Kazem al-Hosseini al-Haeri, al-Sadr's Iran-based spiritual mentor, has said it wasn't yet time for military confrontation with the United States.

Iran is believed to be trying to win influence with both al-Sadr and Iraq's most influential Shiite cleric, the Iranian-born Grand Ayatollah Ali al-Husseini al-Sistani (search).

Iraqis in the southern holy cities have expressed suspicions that offices set up by Iranians ostensibly dispensing charity or providing assistance to Shiite pilgrims might be covers for Iranian government agents.

Mohammad Ali Samadi, a spokesman for the Devotees for Martyrdom, said private Iranian charitable funds were going to a variety of Iraqi groups. He would not specify the groups.

"Iran enjoys a lot of spiritual influence in Iraq," Samadi told The Associated Press. "Iran does offer financial support to Shiites, but in the form of charity. However, it doesn't send any intelligence agents."

Iran long has maintained close ties with a variety of Iraqi groups, including Iraq's largest Shiite group, the Supreme Council of the Islamic Revolution of Iraq (search), and the two powerful Kurdish groups controlling northern Iraq, the Patriotic Union of Kurdistan (search) and the Kurdistan Democratic Party (search). The Kurdish parties are not Shiite.

Iran's contacts with Ahmad Chalabi's Iraqi National Congress (search) led to U.S. accusations that Chalabi, once a U.S. favorite to replace Saddam, passed classified intelligence to Iran. Iran said it has had a constant dialogue with Chalabi, whose group had offices in Tehran before the war, but denied that he handed over sensitive information.