Updated

U.S. forces in Iraq on Wednesday launched a planned and coordinated operation codenamed Iron Hammer that targeted pro-Saddam loyalists, a senior military source told Fox News.

Based on intelligence collected on the ground, U.S. infantry set a number of traps all over Baghdad (search). Several of those traps — monitored from the air and known as NAIs or Named Areas of Interest — were activated almost simultaneously Wednesday night.

In the most dramatic action, about a dozen Bradley armored vehicles used 25mm cannons to destroy a warehouse used by anti-U.S. forces in southern Baghdad. A special forces AC-130 Spectre gunship also took part from the air, targeting the warehouse with precise fire.

"The facility is a known meeting, planning, storage and rendezvous point for belligerent elements currently conducting attacks on coalition forces and infrastructure," the Pentagon (search) said in a statement from Washington.

"The destruction of this structure will deny enemy forces any use of it in the future."

The attack on the warehouse was one of four strikes in Operation Iron Hammer. According to military sources, the other attacks were:

— U.S. soldiers observed a group of people firing several mortar rounds from a truck, who then tried to drive away. An AH-64 Apache helicopter was called in to follow the fugitives and it fired on the vehicle, hitting it. Two terrorists were killed and five others were captured. Plus, Americans seized an 82mm mortar.

— Infantrymen saw another enemy approach and fire three mortar rounds, aimed at harassing U.S. forces. Americans opened fire using small arms and a Bradley armored vehicle. The vehicle was hit several times but managed to disappear in traffic on a highway.

— An American artillery unit fired 12 rounds of 155mm howitzers against an insurgent mortar team that had fired off a few shots in the direction of the "green zone," where the central Coalition military and civilian authority compound is located in Baghdad. This two-square-mile area had been hit by harassing mortar fire on a number of occasions during the past week.

The U.S. offensive came on the same day that a truck bomb exploded at an Italian paramilitary police headquarters in the southern Iraqi city of Nasiriyah (search), which killed 18 Italians and eight Iraqis.

And the U.S. action came one day after America's top soldier in Iraq said attacks against the U.S.-led coalition were increasing and he vowed a tough response.

"The most important message," he continued, "is that we are going to get pretty tough ... but we will do everything possible to minimize the impact on the people of the country," Lt. Gen. Ricardo Sanchez (search) told reporters.

Sanchez said the United States would "send a very clear signal that our intent is to defeat the former regime loyalists, the terrorists and those people that are attacking the coalition and the Iraqi people."

In Washington, administration officials vowed to keep the finish the job of stabilizing Iraq.

"It's a difficult situation," Secretary of State Colin Powell (search) said of security in Iraq. "But we are confident that our commanders will get on top of it and our intelligence experts will be able to penetrate these remnants of the old regime who are trying to destroy the hopes and aspirations of the Iraqi people."

Analysts said the Wednesday offensive was an indication that the U.S. forces were following through on Sanchez's pledge.

"It's great news because it shows we're bringing the fight to them," said retired Col. David Hunt, a Fox News military analyst. Hunt said the attack on the warehouse showed that Americans were getting better human intelligence.

"It's never been a problem on the fight," Hunt said. "The problem has been finding these bad guys and this shows there has been a new offensive started."

Fox News' Dana Lewis and The Associated Press contributed to this report.