Inside Southern Iraq ? More than 60,000 U.S. and British troops invaded southern Iraq, artillery batteries bombarded enemy positions, and Tomahawk cruise missiles blasted Baghdad again Thursday night as the second Gulf War expanded.

Coalition forces suffered their first casualties in a helicopter crash in Kuwait that left 12 Britons and four Americans dead.

And on the second day of Operation Iraqi Freedom, American officials held out the tantalizing possibility that Saddam Hussein had been killed in the initial Wednesday night bombing of Baghdad.

State-run Iraqi television said Saddam survived and met with his top aides to counter the U.S.-led attack. “We are resolved to teach the criminal invaders hard lessons and make them taste painful punishment,” declared the Iraqi military.

U.S. intelligence said Saddam and possibly two of his sons were present inside a suburban Baghdad compound when it was struck and that medical attention was summoned afterward. There was no definitive word whether Saddam was caught in the pre-dawn attack.

The war’s first casualties came when an unarmed transport helicopter was carrying Marines and British troops back to Kuwait after a mission in Iraq, said a U.S. Department of Defense official, who spoke on condition of anonymity.

The crash at 6:40 p.m. CST was probably due to mechanical problems.

While there were no Iraqi chemical or biological attacks Thursday, Iraqi forces fired at least four ineffectual missiles at U.S. positions in Kuwait. Iraqi forces also torched at least nine Iraqi oil wells or pipelines.

Early today, hours after the invasion began, hundreds of allied military vehicles were backed up at the Kuwait-Iraq border. Marines waiting to enter could see a fire burning in the al Rumeila oil fields to the east.

A plume of thick, black smoke stretched south as far as the eye could see. Radio traffic indicated a Marine detachment had been sent to take control of the oil field, but it was unclear this morning whether the effort was successful.

Soldiers from the 3rd Brigade of the 101st Airborne assemble at Camp New Jersey before moving to forward positions Thursday in the Kuwaiti desert. Sixty thousand U.S. Marines, Navy SEALs and British commandos left positions in northern Kuwait and crossed into Iraq.

U.S. officials called Iraq’s military response modest and uncoordinated, suggesting that key aides of Saddam Hussein — perhaps Saddam himself — may have been incapacitated or killed by the precision air attack that opened the war.

That raised the possibility that the war’s duration could be shortened and the cost in lives and property curtailed.

Still, the war was clearly intensifying Thursday.

“Aim point is Baghdad,” Col. Joe Dowdy said as 60,000 Marines, Navy SEALs and British commandos abandoned foxholes and other positions in northern Kuwait, climbed into a snaking convoy of thousands of armored vehicles and rumbled into Iraq.

Mortars and cannon shells screamed overhead — and U.S. infantry troops cheered. Army artillery and Apache helicopter gunships raked Iraqi positions. A Marine unit knocked out an Iraqi 1950s-vintage T-55 tank, eliciting lusty “hoorahs” from officers at headquarters.

Britain joins fighting

In addition, hundreds of British Royal Marine commandos and U.S. Navy SEALs attacked an Iraqi beach at the head of the Persian Gulf.

“Tonight, British servicemen and women are engaged from air, land and sea,” British Prime Minister Tony Blair told his nation during a televised address.

Apparently in reaction to Iraq’s subdued response, the Pentagon launched the limited ground attack ahead of schedule but did not accelerate its much-heralded aerial blitzkrieg.

Instead, U.S. and British forces launched another round of limited air attacks on Baghdad and then began the ground advance into Iraq by the Army’s 3rd Infantry Division, the 1st Marine Expeditionary Force and various British units.

The objective, according to two senior administration officials who requested anonymity, was to oust Saddam and disarm Iraq without causing widespread civilian casualties and immense destruction to Iraq’s economic infrastructure.

The evolving strategy also could place fewer American lives in danger.

President Bush and his aides this morning will consider whether to launch the massive aerial blitzkrieg after darkness falls in Iraq tonight, or to continue using more limited force in hopes that Saddam’s regime will collapse without massive destruction.

“There’s no question we’ve sent the finest of our citizens into harm’s way,” Bush said during a Cabinet meeting at the White House. “They perform with great skill and great bravery. We thank them, we thank their loved ones, we appreciate their sacrifice.”

As darkness fell on Baghdad, another large volley of Tomahawk missiles — more than two dozen — launched by U.S. and British submarines and warships rocked the capital. Heavy explosions shook the city, and dense black smoke rose from several sites.

Precision strikes hit the main presidential palace and the ministry of planning. Other key targets included strongholds of Saddam’s elite Republican Guard and the special security organization headed by Saddam’s son, Qusai.

The International Red Cross said one person was killed and 14 people were wounded during the first wave of U.S. missile strikes; no casualties were immediately reported from the second attack.

Even as the fresh wave of missiles struck Baghdad, CIA analysts concluded that it was Saddam, not one of his doubles, who appeared on Iraqi television shortly after the U.S. attempted to kill him and his top aides in the opening salvo.

The analysts, however, were not sure if the appearance was live or prerecorded — leaving open the question of whether Saddam was alive. Even if he was, Defense Secretary Donald Rumsfeld said, “the days of Saddam Hussein are numbered.”

Second wave

Sirens sounded repeatedly in U.S. bases and Kuwait City. U.S. officials issued several chemical weapons alerts and American troops wore gas masks through much of the day.

Patriot anti-missile missiles intercepted three Iraqi missiles, according to Army Lt. Col. Geoff Ward of the 3rd Infantry Division. Among the troops, cheers and applause greeted each announcement of a Patriot interception.

One missile fell near Camp Commando, a Marine headquarters position in northern Kuwait, carving a 2-foot-deep crater, slicing some overhead power lines, but inflicting no other damage.

Inside one bunker in northern Kuwait, Staff Sgt. Teresa Hawkins, 32, made the sign of the cross as sirens wailed outside.

“This was the first time I’ve been in a war,” she said, “and I was thinking, ‘I could die.'”

Washington plans

After Rumsfeld gave senators a closed-door evening briefing on Capitol Hill, Sen. Ted Stevens, R-Alaska, said, “as the plan evolves, it will be more and more intense, more and more violent and more and more destructive.

“It’s a decision for the Iraqi people as to how much of a battering they will take before they change their leader,” Stevens said.

Sen. Trent Lott, R-Miss., said that before the assaults grow more violent, U.S. military planners want to clear the path with precision strikes. “They have some things they wanted to do, some things they wanted to secure” first.

Earlier, Rumsfeld and Air Force Gen. Richard Myers, chairman of the Joint Chiefs of Staff, emphasized that Iraqi military leaders could spare themselves and their nation much harm if they quickly capitulated.

U.S. intelligence officials also have been telephoning Iraqi Republican Guard officials at home and trying to negotiate their surrender, said administration officials who requested anonymity. In some cases, Arabic-speaking U.S. officials also have called the families of some officers at times when they calculated the soldiers weren’t home and warned them of what could happen if the U.S. assault proceeded.

The Turkish parliament, meanwhile, made Rumsfeld’s task a bit easier, voting to open that country’s airspace to U.S warplanes. Turkish legislators, however, did not address a longstanding U.S. request to let 62,000 troops open a second front by crossing Iraq’s northern border from Turkey.

Rumsfeld also sought to address the Iraqi people, echoing words spoken by Gen. Dwight D. Eisenhower on June 6, 1944, when he announced the World War II invasion of France: “The hour of your liberation is approaching.”

Said Rumsfeld: “To the Iraqi people, let me say that the day of your liberation will soon be at hand.”