The Hezbollah military machine that has been attacking Israel draws much of its strength from two shadowy sources that are proving difficult to cut off: Syria and Iran.

The two countries, which President Bush blames for fomenting terrorism and destabilizing the Middle East, provide Hezbollah with training, weapons and financing, according to Western intelligence officials who are working to stem the flow of aid.

Rep. Mike Rogers, R-Mich., a House Intelligence Committee member who was briefed on the Middle East situation during a recent trip to Iraq, said Syria has more than 1,000 agents in southern Lebanon, working either directly for Syrian intelligence or compensated by Syria for information. He says they are there "to cause trouble" and help prop up Hezbollah militarily.

Lebanon is two-thirds the size of Connecticut. In a country that small, Rogers said, "a thousand intelligence agents is unbelievable. It's huge."

CountryWatch: Israel | Lebanon | Syria | Iran

Visit FOXNews.com's Mideast Center for more in-depth coverage.

Along with Syria's agents, Iran's well-trained Revolutionary Guard is believed to be providing military advisers to Hezbollah, with some level of coordination with Syria, according to U.S. officials and Anthony Cordesman, a Middle East expert with the Washington-based Center for Strategic and International Studies.

The officials spoke on condition of anonymity because of the subject's sensitivity.

Cordesman said the Iranian role has evolved over time. Earlier, significant numbers of Iranians could be seen operating at terrorist training camps in Lebanon's Bekaa Valley. Syria provided them safe haven in the region. "Now, what you have is people who are less visible," he said.

While intelligence agencies may try to pin down such details with spies, eavesdropping equipment and overhead surveillance, the details are among any government's most classified secrets. And some of what is public may be misinformation.

"I'll be perfectly blunt: Israeli intelligence is political, and you can't trust it," Cordesman said.

The United States lists Hezbollah as a terror organization. Yet the complicated 24-year-old Shiite Muslim organization has stepped in to fill vacuums left by the country's anemic government and controls much of the southern part of Lebanon, operating schools, health care and other social services.

It was created to counter Israeli occupying forces after Israel's 1982 invasion of Lebanon and still provides much of the security along the border with the Jewish state. Tensions have mounted between Israel and Hezbollah's base in southern Lebanon since Hezbollah's brazen July 12 raid into northern Israel during which it kidnapped two Israeli soldiers and killed eight others.

Experts have disputed claims from Hezbollah's leader, Sheik Hassan Nasrallah, who has said repeatedly that his group has more than 12,000 rockets.

Other estimates suggest that the supply of rockets rose to 10,000 this year. That includes some Iranian-made rockets with a range of perhaps as much as 45 miles, but the vast majority — the Katyusha-type rockets — have a range of less than 20 miles.

Israel says Hezbollah has missiles and rockets that can go much farther. Israeli officials said the naval warship struck Friday was hit with an Iranian-made, radar-guided C-802 cruise missile, which has a range of up to 74 miles. Iran denies the claim, and U.S. officials have no information to confirm the missile was the C-802.

Numerous security and intelligence experts caution that estimates on Hezbollah's rocket arsenal aren't firm because they're based on calculations about the potential volume of known weapons shipments, rather than any actual count. Israel has been trying to cut off any resupply by destroying land routes from Syria into Lebanon.

Hezbollah can do limited reconnaissance. The group launched at least two unmanned aerial vehicles in 2004 and in 2005. Both Hezbollah and Israel have said the light, low-flying crafts were made by the group itself, while American analysts believe the drones were Iranian-made.

So far, U.S. officials and other experts have seen no sign that the group's drones have been armed with weapons.

How Hezbollah makes and spends its money is difficult for Western officials to determine. Hezbollah gets significant support from Iran and from Lebanese people living abroad, and more limited financing from Syria, a relatively poor country.

One senior U.S. intelligence official said the group has access to several hundred million dollars a year, much of it going to the social service network in southern Lebanon rather than arms and terrorism. But that money could be diverted to terror or military operations.

The organization also has been linked to almost every type of organized crime, including drug trafficking, drug counterfeiting and selling stolen baby formula.