WASHINGTON -- Stepping up the pressure on President Saddam Hussein, a U.S. F-15 shot down an Iraqi fighter-bomber over Iraq yesterday.
President Bush warned that allied forces would fire on any other aircraft that defy the ban on Iraqi military flights imposed by the forces that drove Baghdad's troops from Kuwait.
The attack, the first aerial combat since hostilities were suspended on Feb. 28, came as rebellions continued in Iraq. A senior administration official said that insurrections in the north and south were stronger than Washington had anticipated.
Iran is aiding southern Shiite Muslim rebels, while Mr. Hussein has been forced to shift military units north to prevent Kurdish rebels from taking control of major cities and to protect his oil fields, said the official, who spoke on condition of anonymity.
The downing of the Iraqi plane yesterday added a significant military element to what had been a verbal and diplomatic effort by Mr. Bush to put pressure on Mr. Hussein in the hope that his Arab Baath Socialist Party and the Iraqi military would remove him from power.
Administration officials said the president believes that he can walk the fine line between that goal and the risk that by hampering Baghdad's ability to fight the insurrections, the United States could end up with an Iraq torn by civil war and without a central authority.
The White House and the Pentagon said that two Soviet-made Iraqi Su-22 planes took off yesterday from an air base in northern Iraq and were detected by an AWACS surveillance plane.
The AWACS sent a variation of the F-15 fighter, the F-15C, to intercept the Iraqi fighter-bombers. It shot one of them down, officials said. The other was allowed to land. It was not immediately known whether the pilot of the downed aircraft had survived.
Mr. Bush, during a photo session at the White House with President Lech Walesa of Poland, repeated the administration's position that the flights violated an agreement reached March 3 by Iraqi generals and alliance commanders headed by Gen. H. Norman Schwarzkopf, the U.S. military chief in the gulf.
"If other planes violate the agreement, they will be shot down," Mr. Bush said.
The United States has twice warned Iraq not to use any of its fixed-wing military aircraft.
Mr. Bush has also warned Baghdad not to use combat helicopters to attack rebel positions, but rebel spokesmen in exile said that those attacks continue.
The incident yesterday was the first overt military action by U.S. forces that interfered with Iraqi military activity aimed at putting down the insurrections.
Although the United States has said its ban on Iraqi military flights is intended to protect U.S. forces, the jet shot down yesterday was hit near Tikrit, Mr. Hussein's hometown, about 1,000 miles from the allied occupation zone in southern Iraq.
Officials in the Bush administration said they believed that the Iraqi military would eventually assert control over the country. But they expressed hope that the insurrections would weaken Mr. Hussein enough that he would be overthrown by the end of the year.
After Mr. Hussein gave a speech last week talking of democratic reform, administration officials interpreted his remarks as a "near desperate" move.
The official said that Mr. Hussein had strengthened his heavily damaged army by melding the Republican Guards, his toughest forces, into other units of the regular army.
There have been regular reports on the fighting from Kurdish groups in exile and from other indirect informants. But there is no firsthand confirmation of these reports.
The senior official said that rebel forces in the north appeared to be doing well in the battle for Kut, a city on the supply lines from Baghdad to the north, and that they were at least on the outskirts of Kirkuk.
Kurdish opposition forces say they have captured both of those cities and said yesterday that they were strengthening their control of Kirkuk.
Iran's news agency, monitored by the British Broadcasting Corp., quoted the rebels as saying that they were under heavy fire from Iraqi units, including helicopters using napalm and white phosphorus bombs.
In London, a spokesman for the Kurdistan Democratic Party said that the only remaining Iraqi resistance inside Kirkuk was from the headquarters of the 1st Army Corps.
In Damascus, officials of Kurdish rebel groups said they now control all of Kurdistan, from the town of Zakho, on the Turkish border in the extreme north, to Khanaqin, on the Iranian border, ++ 90 miles northeast of Baghdad. But they said the region's largest city, Mosul, remained under government control.