RIYADH, Saudi Arabia -- The U.S.-led coalition launched an all-out ground campaign against Iraq early today, moving forces by land, sea and air just hours after a deadline passed for Iraq to withdraw from Kuwait, military officials said.
The invasion of Iraqi-held territory began about 4 a.m. (8 p.m. EST) and gave U.S. infantry and amphibious forces the cover of darkness for what Defense Secretary Dick Cheney described as a "massive ground operation," involving forces from several allied nations.
Mr. Cheney, speaking at a Pentagon briefing, announced a news blackout on all details about the campaign in order to prevent Iraq from gaining any knowledge about conditions on the battlefield. He said commanders assumed that Iraq remained "confused" by events, operations that are almost certain to include invasions occurring simultaneously along several routes.
The defense secretary said the ground operation was designed to cause a minimum number of allied casualties, but he described Iraq's estimated 500,000 troops in Kuwait as "well-equipped, well-fortified."
"I would not want to underestimate the difficulties of the task at all," he said.
Mr. Cheney deliberately left unclear the exact time when the ground assault began. But it apparently involved large numbers of forces that were activated at different times and began to move forward at varying speeds, according to a plan refined over a period of many weeks by officers at the U.S. military command in Riyadh.
Gen. H. Norman Schwarzkopf, commander of allied forces, chose the starting date and time well in advance of the operation's launch, and well before expiration of the deadline at 8 p.m. yesterday (noon EST) for Iraq to begin an unconditional withdrawal, Mr. Cheney said.
He said the schedule remained subject to change until the last moment, depending on factors ranging from the weather to possible diplomatic breakthroughs. "Up until noon today [Saturday], the president had the option to say, 'Stop,' " Mr. Cheney said.
U.S. forces began moving after armored units plowed through barriers to open the way for infantry, tanks and artillery to pour into Iraqi-held territory as part of a strategy to attack from several directions. In the hours leading up to the invasion, allied aircraft carried out a record number of bombing missions in and around Kuwait, targeting Iraq's best-equipped units.
President Bush said he authorized General Schwarzkopf to use "all forces available, including ground forces," to launch an operation that the president said would be carried out "swiftly and decisively."
According to Pentagon officials, reports from the United Nations that Iraq was willing to accept at least some of the conditions set by Mr. Bush were never reflected in the actions by Iraqi troops inside Kuwait. Rear Adm. Mike McConnell, the Pentagon's chief of intelligence, said, "We have seen no movement at all."
The timing of the assault appeared to be influenced by allegations that Iraq was carrying out summary executions of Kuwaiti civilians and systematically destroying the country's oil industry and drinking-water plants.
While officers in Saudi Arabia said yesterday that they continued to follow well-established battle plans, the pace of operations had accelerated throughout the day and appeared to be influenced by the allegations of Iraqi atrocities.
Marine Brig. Gen. Richard I. Neal, the U.S. military spokesman in Riyadh, said at a briefing yesterday that executions had begun within the last two days and were directed against civilians stopped at random as well as against people who had been interrogated in the past.
The reports of executions came one day after the military command said Iraq was setting fires to Kuwait's oil wells and destroying shipping terminals and other facilities, evidence that Iraqi President Saddam Hussein was carrying out a threat to keep Kuwait or destroy it.
Fires were reported burning at 200 wellheads, 50 more than the day before, and at high-pressure wells that could require weeks or months to burn themselves out. They spewed black smoke that colored skies a sickly gray as far away as the Emirate of Qatar, more than 300 miles to the south, and produced a thin rain of soot.
Smoke could hamper helicopters and aircraft assigned to support infantry by striking Iraqi tanks and artillery, but General Neal suggested that allied forces could avoid the affected areas and maintained that there would no significant impact on ground operations.
At least some of the smoke came from allied jets dropping napalm to set fire to trenches filled with oil. The military command was counting on being able to burn off the oil to undo Iraq's strategy of using the trenches to trap an invasion force.
Meanwhile yesterday, the command released new estimates of the effects of around-the-clock air strikes against Iraqi units. General Neal said the equipment destroyed included the following:
* 1,685 tanks, 39 percent of the estimated total of 4,200 tanks in and around Kuwait.