Saddam Hussein's regime is moving more surface-to-air missile batteries to Iraq's "no fly" zones, possibly in an effort to blow patrolling U.S. and British pilots out of the sky, the Pentagon said Monday.

The rogue nation’s repositioning of its air defenses over the last several days are the largest such movements in the past couple of years, Gen. Richard Myers, chairman of the Joint Chiefs of Staff, told a news conference.

The newly arrived missile batteries have been involved in recent confrontations involving U.S. pilots, he said.

Myers described the threat posed by the extra surface-to-air missiles in Iraq.

"If they're moved inside the 'no fly' zones, obviously, that increases risks to the pilots that are patrolling in those zones," he said. "And that's what's been happening. And beyond that, I don't want to get into the specifics of exactly where." He added that they were in both the north and south.

Myers said allied pilots in northern Iraq were threatened by Iraqi air defenses three times since April 1.

"In one case, on the 19th, our fighters launched two missiles at a surface-to-air missile system near Mosul," Myers said. "And this particular system had threatened them during their flight."

A week ago an allied air patrol in southern Iraq "was forced to respond" with a guided bomb strike on a surface-to-air missile system radar, he said. These incidents involved some of the new surface-to-air missile batteries, he said.

Last year Iraqi air defenders frequently challenged allied air patrols by targeting them with radars or firing anti-aircraft artillery guns or surface-to-air missiles. But there have been relatively few challenges this year. The U.S. attack on April 15 was the first in southern Iraq since Jan. 21.

U.S. and British warplanes have patrolled "no fly" zones in northern and southern Iraq for more than a decade since the 1991 Gulf War. The zones, not recognized by Baghdad, were set up to protect Kurds in the north and Shiite Muslims in the south from attacks by Saddam’s forces.

American and British warplanes have routinely bombed Iraqi air defenses in retaliation for what the United States and Britain have called repeated challenges to the aircraft. The Iraqi radars have often been the target of the Western attacks.

Despite the incidents, Western officials say the "no fly" zones have been very successful in defending the Iraqi minority groups. Two Kurdish groups are sharing control of northern Iraq, and Saddam’s forces are operating in only a limited capacity in the south.

Iraqi dissidents and Arab news reports say leaders of the two main Kurdish parties that control northern Iraq met with U.S. officials last week to coordinate efforts to remove Saddam from power.

Masoud Barzani, leader of the Kurdish Democratic Party, and Jalal Talabani, leader of the Patriotic Union of Kurdistan, also discussed plans for a government that would replace Saddam's regime once the Iraqi leader is ousted, the Iraqi dissidents told The Associated Press.

On Sunday, the London-based Asharq Al-Awsat newspaper reported that both Barzani and Talabani met officials from the Pentagon, the State Department and the CIA in Germany last week.

Defense Secretary Donald H. Rumsfeld, speaking at the same news conference with Myers, said he was not aware of any "notable difference" recently in Saddam's behavior and the posture of his military.

"He tends to move things around and do things that are inconsistent with the U.N. resolutions, and his rhetoric has historically been provocative and favoring terrorists," Rumsfeld said.

President Bush has declared Saddam a menace to the world community and vowed to remove him as Iraq's leader, although the administration says it has not yet decided how that goal will be achieved.

When Bush took office in January 2001, Saddam increased his challenges to allied air patrols over Iraq. Bush responded on Feb. 16, 2001 by ordering a coordinated series of strikes on air defense radars and other targets in and around Baghdad. Officials said later the attacks were in part a response to concern that Iraq had upgraded its air defense network through the use of Chinese-supplied fiber-optic cables.

Asked Monday whether the Chinese were still helping Iraq, Rumsfeld replied, "I don't know that they've stopped."

The Associated Press contributed to this report.