With sandstorms finally ended and a new front opened in the north, U.S. commanders said Thursday they would swiftly intensify attacks on Iraqi forces. In the south, British troops destroyed 14 Iraqi tanks trying to break out of the besieged city of Basra. In Kurdish-controlled northern Iraq , 1,000 paratroopers from the Army's 173rd Airborne Brigade airdropped overnight onto an airfield that they were busy securing Thursday. It is the first large deployment of U.S. ground troops in the region; previously, only small groups of U.S. Special Forces were operating along with allied Kurdish fighters.

In central Iraq, where huge Army and Marine forces are gradually closing in on Baghdad, U.S. commanders were buoyed by arrival of good weather.

"You'll certainly see us increase our activity in the coming hours, days, given the clearing weather," an official at U.S. Central Command said, speaking on condition on anonymity.

Outside Karbala, southwest of Baghdad, small groups of Iraqi armored personnel carriers approached American positions but were hit by U.S. warplanes before getting within 10 miles.

"I can't believe they keep doing this. It's suicide to come at us like this," said Lt. Eric Hooper of Albany, Ga.

In southern Iraq, British forces destroyed 14 Iraqi tanks that streamed out of the besieged city of Basra overnight, according to a British spokesman, Group Capt. Al Lockwood.

It was the third time this week that Iraqi columns have been attacked while trying to get out of Basra, which has been ringed by British troops.

"The enemy's options are now limited," Lockwood said of the failed breakouts. "It's a suicidal approach which is irrational... Military cohesion is sadly lacking."

Lockwood said militiamen of the ruling Baath were threatening families of Iraqi soldiers to force them into driving the military vehicles out of Basra.

"They are obviously coercing them into this action, whereas in fact we would have wished them to surrender," he said.

Aid for Basra and other parts of southern Iraq is supposed to come through the port of Umm Qasr, which has been captured by the allies. However, British officers said Thursday that Iraqi mines have been discovered in the port, delaying the arrival of a ship carrying 200 tons of aid until minesweeping is completed.

Near the southern Iraq city of An Nasiriyah, more than 30 U.S. Marines were injured, two seriously, in an accidental exchange of fire between American units, according to reporters for French and British media who were with the Marines.

ITV correspondent James Mates said two groups of Marines were dispatched during the night to repel an Iraqi contingent, but ended up firing at each other.

The U.S. Central Command said it had no information on the report.

Baghdad was jolted by more explosions Thursday; aircraft were heard overhead while anti-aircraft fire lit up the dawn sky.

Iraq's health minister, Omeed Medhat Mubarak, said 36 civilians were killed and 215 injured Wednesday in allied air strikes on Baghdad, including what Iraq said was a U.S. cruise missile strike that hit a market area.

Nationwide, Mubarak said about 350 civilians had been killed and more than 4,000 injured since the war began. "Neither the Bush administration nor their bombs are 'smart,'" said Mubarak, accusing the United States and Britain of deliberately targeting civilians.

A U.S. military spokesman, Lt. Col. Al Worley, said coalition forces have gone to great lengths to avoid civilian casualties.

"War is an ugly thing and innocent people die, that is an unfortunate thing," he told the BBC. "If you look to the casualty reports coming out of Baghdad, as many bombs as we've dropped and so few casualties we've had, that's a testament right there to our precision bombing."

He said the Iraqi regime was culpable because it has placed military equipment close to residential neighborhoods.

On Thursday, skies cleared over Baghdad after one of the worst sandstorms in memory. For some residents, the blue skies heightened fears of more intensive air strikes.

At his retreat at Camp David, President Bush conferred on strategy and postwar plans with his closest ally, British Prime Minister Tony Blair . One potentially divisive topic: how big a role to give the United Nations in Iraq's reconstruction.

The two leaders talked privately Wednesday night, and planned a series of meetings Thursday. Their principal foreign policy advisers, Secretary of State Colin Powell and Foreign Secretary Jack Straw, also were discussing war strategy and plans for Iraq's reconstruction.

Blair has advocated a more extensive role for the United Nations in administering postwar Iraq than has Bush.

PHOTO CAPTION

A F/A-18 Hornet launched from the USS Harry S. Truman takes off at sunrise for a strike against Iraq , Thursday, March 27, 2003. The squadrons of the carrier group in the eastern Mediteranean have stepped up flight operations in support of 'Operation Iraqi Freedom.' U.S. forces edged closer to Baghdad on several routes Thursday clashing with Iraqi troops and preparing for a possible confrontation with Saddam Hussein's Republican Guard.(AP Photo/Markus Schreiber)