Baghdad, Iraq ? The capture of dozens of guerrilla leaders has left the U.S. military with a murky picture of a shadowy resistance here, with American and Iraqi officials divided about whether Iraqis or foreign fighters are responsible for recent attacks.

A spate of arrests — including the capture of Saddam Hussein — have broken rebel command networks and forced fighters underground, a top U.S. military official told The Associated Press. Yet attacks persist, crowned by a bold daylight assault this weekend on security compounds in Fallujah that freed 87 prisoners and killed 25 people, mostly police.

U.S. and Iraqi officials have begun focusing on foreign fighters, especially al-Qaida-linked operative Abu Musab al-Zarqawi, a Jordanian blamed for a series of devastating car bombs that U.S. officials say were aimed at starting civil war.

The emergence of al-Zarqawi has triggered a spate of competing statements by U.S. and Iraqi officials, with some blaming foreign terrorists for the car bombs and Saturday’s guerrilla raid and others pointing to Saddam loyalists.

“We’ve really gotten into the guts of the insurgency,” said a U.S. military official, who spoke on condition of anonymity. The Dec. 13 capture of Saddam helped the Americans identify and capture a slew of operational-level leaders.

The string of arrests convinced some rebels to give up the fight, while others may have turned to radical politics or religion to undermine the occupation, the official said.

At the same time, U.S. officials here and in Washington have acknowledged a handful of Iraqi rebel groups remain active in Iraq.

They include:

l Muntada al-Wilaya, a Shiite group that has grown less troublesome since its leader’s capture.

As a sandstorm moves over central Iraq, U.S. soldiers guard a checkpoint near the Iraqi Police Academy complex in Baghdad. Despite headway on preventing guerrilla attacks, troops do not know who is behind the daily violence.

l The Return Party of former Saddam political allies that continues to mount attacks and distribute leaflets warning against cooperating with Americans.

l Muhammad’s Army, an umbrella group of former Iraqi intelligence and security agents.

l And Ansar al-Sunna Army, which claimed responsibility for the Feb. 1 bombings in the northern city of Irbil that killed 109 people.