With sandstorms finally ended and a new front opened in the north, U.S. commanders said today 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 Kurd-ish-controlled northern Iraq, 1,000 Rangers and other paratroopers from the Army's 173rd Airborne Brigade airdropped overnight onto an airfield that they were busy securing today. 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.

In a news briefing at Central Command, Brig. Gen. Vincent Brooks said several U.S. units battled successfully against Iraqi forces today, destroying vehicles and inflicting casualties. He said some Marines were injured in fighting near the southern city of An Nasiriyah, but gave no details.

Brooks accused the Iraqis of increasingly flagrant violations of international conventions. Iraqi security forces were seizing children in order to force their fathers to join the military, and were executing men who resisted, he said.

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.

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.

''The enemy's options are now limited,'' Lockwood said of the failed breakouts. ''Military cohesion is sadly lacking.''

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. British officers said Iraqi mines have been discovered in the port, delaying the arrival of a ship carrying 200 tons of aid until minesweeping is completed.

Near 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.

Brooks said U.S. officials were investigating the report.

Baghdad was jolted by more explosions today.

Skies cleared today over Baghdad after one of the worst sandstorms in memory and the city was jolted by a series of explosions.

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.

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.

Brook said U.S. investigators were trying to determine whether a U.S. missile might have hit the Baghdad market area on Wednesday. He suggested the damage might have been caused by an errant Iraqi surface-to-air missile, or even by a deliberate Iraqi action aimed at discrediting the United States.

In London, British defense officials said the discovery of more chemical protection suits suggest Iraq was prepared to use chemical weapons against advancing coalition forces.