In a televised speech, Lt. Gen. Aboud Qanbar, who is leading the new crackdown, also announced the closing of Iraq’s borders with Iran and Syria, an extension of the curfew in Baghdad by an hour, and the setup of new checkpoints run by the Defense and Interior Ministries, both of which General Qanbar said he now controlled.

He said the government would break into homes and cars it deemed dangerous, open mail and eavesdrop on phone calls.

General Qanbar did not mention the role American forces would play in the crackdown, but his remarks were clearly timed to coincide with more aggressive efforts by American troops on the streets of Baghdad. The Americans have been establishing outposts — called joint security stations — to work alongside the Iraqi Army and police to end the sectarian bloodletting.

On Tuesday, senior American officers expressed surprise about the plan to resettle people who had moved from their homes amid sectarian cleansing. But they declined to be identified, saying they did not want to contradict the Iraqi general.

General Qanbar indicated that the plan would be carried out evenly across Baghdad. But critics said Prime Minister Nuri Kamal al-Maliki, who has come under intense criticism for pursuing a sectarian Shiite agenda, might be trying to appease his detractors and may not actually carry out the plan. Some feared that his government might not apply the same pressure to residents of Shiite areas.

Since the bombing of a sacred Shiite shrine in Samarra a year ago, the sectarian map of Baghdad has been almost completely redrawn, as Shiites pushed Sunnis from neighborhood after neighborhood.

The general faces a monumental task. Even without the daily violence, continuing sectarian killings and a lack of security forces to perform basic policing tasks, there is no system in place to investigate the veracity of people’s claims. In addition, thousands of people took over homes immediately after the invasion, claiming basic squatters’ rights.

Under the general’s plan, people who have illegally occupied homes will have 15 days to leave. While they are there, he said, they must protect the home, not steal from it or damage it.

"Anyone who does not follow this law will be treated according to the antiterrorism laws," he said, adding that the government would set up committees to determine ownership.

General Qanbar, wearing a camouflage uniform and a red staff commander’s beret, made it clear that he reported only to the prime minister. Mr. Maliki appointed him as the overall Iraqi commander for forces in Baghdad in January. With the extraordinary powers he claimed, an increasing amount of authority is now consolidated in the prime minister’s office.

At least 10 formerly mixed neighborhoods in Baghdad are now almost entirely Shiite. East Baghdad, vulnerable to attack from Shiites in the Sadr City stronghold, is almost entirely under Shiite control. West Baghdad, where there are still fierce sectarian clashes, is a war zone of divided neighborhoods, where crossing from a Shiite enclave to a Sunni enclave without the right identification, or the other way around, can mean death.

The Iraqi cabinet proposed a plan last year to create space in West Baghdad for some 3,000 Sunni families who had been displaced, but nothing came of it.

It is impossible to know exactly how many people have been forced from their homes, but estimates by Iraqi and American officials range from tens of thousands to as high as 200,000.

Samantha Power, a public policy professor at the John F. Kennedy School of Government who has written widely on genocide, described the plan as either a public relations ploy that would never be enforced, or worse, a prelude to more sectarian cleansing and catastrophe.

"To do this in the middle of a war when tempers have been inflamed and militarization is ubiquitous seems to be putting the cart before the horse," she said. "You haven’t stopped the willingness to ethnically cleanse, but you’re imposing the moral hazard of ethnic cleansing on the cleansee? Unless you create security first, you are paving the way for a potential massacre of returnees."

General Qanbar did not explain how the houses would be checked except to say that people in homes that did not belong to them must have currently dated letters from the owners.

Apart from the resettlement issue, he promised swift justice for law breakers.

"All the people who have done terrorist operations or major crimes like killing, stealing, rape, kidnapping, bombing public or private buildings and who have bought, sold or made weapons or bullets, we will hand them over to the Major Crimes Court, which will hold emergency trials," he said.

The general also said all convoys — even those from the government — would be subject to search at the checkpoints. Government security forces have been infiltrated by criminals, militants and Shiite militias.

If they refuse to stop, he said, "They will be treated as illegals."

Only hours before he spoke, there was more carnage on the streets of Baghdad.

In one attack, a suicide bomber killed 17 people and wounded 40 more at a Trade Ministry food warehouse in a poor Shiite neighborhood. At the site of the blast, there was little faith in the promises of politicians.

"I think the situation will get worse, and we can tell in advance that the security plan is a failure," said Muhammad Saadi, 28, a worker at the warehouse. "The government can do nothing to stop the suicide bombers."

Around him, the white foam of a fire extinguisher mingled with pools of blood, as moaning voices filled the air.

In recent days, new checkpoints have appeared around the city with tanks and heavy weapons meant to demonstrate a powerful show of force.

But residents expressed skepticism that checkpoints could provide any real security.

"These checkpoints are useless," said Ahmed Aboud, 45. "You can bribe them with 5,000 Iraqi dinars and bring in all the explosives you want."

New Tape from Qaeda Figure

CAIRO, Feb. 13 (AP) — Al Qaeda’s second in command, Ayman al-Zawahri, said President Bush was an alcoholic and a lying gambler who wagered on Iraq and lost, according to a new audiotape released Tuesday.

Mr. Zawahri said in the tape that Mr. Bush has been forced to admit his failure in Iraq after he repeated the "lie, which he became addicted to, that he is winning" in Iraq and Afghanistan.

"Bush suffers from an addictive personality and was an alcoholic," he said.

"I don’t know his present condition," Mr. Zawahri added, "but the one who examines his personality finds that he is addicted to two other faults — lying and gambling."

Mr. Bush, who is 60, has acknowledged that he had a problem with drinking but has said he gave up alcohol when he was 40.

The 41-minute audiotape could not immediately be authenticated; The Associated Press found it on a Web site commonly used by insurgent groups, and it carried the logo of the multimedia arm of Al Qaeda.

Khalid al-Ansary and Damien Cave contributed reporting.