U.S. Marines were dug into defensive positions south of Kuwait's border with Iraq on Thursday, poised to launch an expected ground invasion.

The Marines took up positions in the so-called "dispersing area" in the desert Tuesday afternoon, just hours after President Bush gave Saddam Hussein a 48-hour deadline to leave Iraq or face war.

Some people spend 20 years, some people spend 20 months, some people spend 20 weeks training for this moment," said Capt. Daniel Schmitt, the commanding officer of the Weapons Company.

"This is what we came to do - have a good time ... and take it to the enemy."

Schmitt told his Marines they were the toe of the boot that would kick Saddam out of Iraq.

"This is what we came to do - have a good time ... and take it to the enemy," he said.

"Let the chaos ... reign," he said. "That's what we thrive in."

On Tuesday, as the Marines of the 7th Regiment left a staging area where they had lived for two months, they threw out everything they considered extraneous to battle, from books and newspapers to board games and a lawn chair.

A huge convoy of trucks, tanks and armored vehicles drove across the Kuwaiti desert and dropped the Marines off in the area where they were to wait until being called on to attack.

The Marines, happy to be doing something after months of waiting, quickly took out spades and pickaxes and spent hours digging deep holes for their weapons and shallow sleeping holes for themselves.

Many Marines expected Saddam might launch a chemical or biological attack. They were ordered Tuesday to put on suits designed to protect against those attacks - and expected to keep the heavy suits on for much of the war.

On Thursday, everyone was ordered to put on gas masks as Iraq fired missiles toward American troops just across the Kuwaiti border. The all-clear was sounded after about 10 minutes.

Before the alert, many Marines had sat eating or sleeping in the sun with helmets and flak jackets on, trying to get as much rest and food as possible before they were called into battle.

Cpl. Joshua Longoria of Mansfield, Texas, sitting in a hole with his mortar system, said his feelings ranged from anxiety to the monotony of "waiting again, just in a different location."

The 22-year-old said he wanted the war to start so he could get home quicker, to his wife and 5-month-old daughter.

Some Marines were simply excited to begin fighting, something they had trained to do for years, and occasional screams of "Let's get it on!" came from some of their weapons holes.

Others said they had no other way back to the United States but through Iraq.

"Vegas is that way," Cpl. Matt Nale, 31, of Seattle, said, pointing north to the border. "That's my way to Vegas.