NEAR FALLUJAH, Iraq -- US warplanes pounded Fallujah late yesterday in what residents called the strongest attacks in months, as more than 10,000 American soldiers and Marines massed for an expected assault. Iraq's prime minister warned the "window is closing" to avert an offensive.
Residents reached by telephone said the aircraft were striking targets in the central city market that had not been hit since April, as well as other neighborhoods. There was no confirmation from US officials.
Earlier yesterday, residents said US planes dropped leaflets urging women and children to leave the city, which is 40 miles west of Baghdad.
As pressure mounted on the guerrilla stronghold, the insurgents struck back, killing one US soldier and wounding five in a rocket attack. Clashes were reported at other checkpoints around the city and in the east and north of Fallujah late in the day.
In Baghdad, a huge column of black smoke rose over the city's Karrada district after midnight, and residents said they heard heavy gunfire, presumably between police and militants. No one answered the phone at the local police station.
For the past three nights, long convoys of American soldiers from Baghdad and Baqubah have rolled onto a dust-blown base on the outskirts of Fallujah, a city that has become the symbol of Iraqi resistance. US commanders here have been coordinating plans either to fight their way into the city or isolate it from the rest of Iraq's Sunni Muslim heartland.
If they fight, American troops will face an estimated 3,000 insurgents dug in behind defenses and booby traps. Military planners believe there are about 1,200 hard-core insurgents in Fallujah -- at least half of them Iraqis. They are bolstered by insurgent cells with up to 2,000 fighters in the surrounding towns and countryside.
In Brussels, Iraq's interim prime minister, Ayad Allawi, warned that the "window is closing" to avert an assault on Fallujah. Allawi must give the final go-ahead for the offensive, part of a campaign to curb the insurgency ahead of national elections planned for January.
Sunni clerics have threatened to boycott the election if Fallujah is attacked, and UN Secretary-General Kofi Annan has warned US, British, and Iraqi authorities that a military campaign and "increased insurgent violence" could put elections at risk.
US aircraft struck targets around Fallujah in numerous raids starting late Thursday and continuing into last night. Targets included a system of barriers rigged with bombs, a command post, suspected fighting positions, and a weapons cache, according to Lieutenant Nathan Braden of the 1st Marine Division.
Late yesterday, US jets went into action again, striking several targets in the Jolan sector of northern Fallujah, residents said. Jolan is considered one of the most heavily defended neighborhoods in the city.
As the night dragged on, the attack was expanded to targets in many areas of city, according to residents. Artillery fire could also be heard. The drone of US aircraft heading toward Fallujah could be heard over Baghdad.
Earlier, mortar shells exploded on a small US base at Saqlawiyah, west of Fallujah, the military said. US troops returned fire, killing a number of insurgents, the military said.
Iraqi authorities closed a border crossing point with Syria, and US troops set up checkpoints along major routes into the city. Marines fired on a civilian vehicle that did not stop at a checkpoint in Fallujah, killing an Iraqi woman and wounding her husband, according to the US military and witnesses. The driver did not notice the checkpoint, witnesses said.
"Marines fire upon vehicles only as a last resort when verbal and visual warnings to stop fail. Such was the case today," the Marines said in a statement.
The violence came a day after two Marines were killed and four wounded in fighting west of Baghdad. The Marine command gave no further details, citing security.
Allawi has demanded that Fallujah hand over foreign extremists, including Jordanian terrorist leader Abu Musab al-Zarqawi and his followers, and allow government troops to enter the city.
"We intend to liberate the people and to bring the rule of law to Fallujah," Allawi said after meeting with European Union leaders.
EU leaders responded with a $39 million offer to fund the January elections, including training for Iraqi vote monitors.