BAGHDAD — The United States and Iran broke a 27-year diplomatic freeze Monday with a four-hour meeting about Iraqi security. The American envoy said there was broad policy agreement, but that Iran must stop arming and financing militants who are attacking U.S. and Iraqi forces.

Iranian Ambassador Hassan Kazemi Qomi said that the two sides would meet again in less than a month. U.S. Ambassador Ryan Crocker said Washington would decide only after the Iraqi government issued an invitation.

"We don't have a formal invitation to respond to just yet, so it doesn't make sense to respond to what we don't have," Crocker told reporters after the meeting.

The talks in the Green Zone offices of Iraqi Prime Minister Nouri al-Maliki were the first formal and scheduled meeting between Iranian and American government officials since the United States broke diplomatic relations with Tehran after the 1979 Islamic Revolution and the seizure of the U.S. Embassy.

An AP reporter who witnessed the opening of the session said Crocker and Kazemi shook hands.

BUSH PAYS TRIBUTE TO FALLEN U.S. TROOPS

ARLINGTON, Va. — President Bush on Monday honored U.S. troops who have fought and died for freedom and expressed his steely resolve to succeed in the war in Iraq. "As before in our history, Americans find ourselves under attack and underestimated," he said.

Bush marked his sixth Memorial Day as a wartime president with a somber speech at Arlington National Cemetery. He said he hoped the United States will always prove worthy of the sacrifices fallen troops have made, and recognized the grief suffered by families and friends of troops killed in war, most recently in Afghanistan and Iraq.

"Now this hallowed ground receives a new generation of heroes — men and women who gave their lives in places such as Kabul and Kandahar, Baghdad and Ramadi," he said. "Like those who came before them, they did not want war, but they answered the call when it came. They believed in something larger than themselves. They fought for our country, and our country unites to mourn them as one."

The president's motorcade was greeted at Arlington by scores of tourists who waved at Bush. Just before his limousine crossed over the Potomac River into Virginia, a man held up a sign saying, "Bring our troops home."

Members of the armed forces carrying rifles fitted with bayonets stood at attention as Bush's motorcade winded its way through rows of white tombstones marked with tiny American flags. Some soldiers were astride horses that flinched when canons were fired, sending bluish white smoke over the cemetery.

SUICIDE CAR BOMBER KILLS 21 IN BAGHDAD

BAGHDAD — A suicide car bomber struck a busy Baghdad commercial district Monday, killing at least 21 people, setting vehicles on fire and damaging a nearby Sunni shrine, police and hospital officials said.

The blast went off at 2 p.m. in the Sinak market area on the east side of the Tigris River, just as U.S. and Iranian diplomats were wrapping up a historic meeting aimed at ending the violence wracking the country.

Insurgents carried out several mortar and car bombing attacks throughout the capital Monday and even waged a lengthy gun battle with police in broad daylight. The wave of violence, which killed 36 people across Baghdad, came despite a nearly 15-week-old U.S.-led security crackdown in the city.

Another 33 bullet-riddled bodies were found handcuffed, blindfolded and showing signs of torture in different parts of Baghdad, the apparent victims of ongoing sectarian violence.

The deadliest attack Monday was the car bombing in the Sinak district, near the Abdul-Qadir al-Gailani mosque.

CLOSE RACE IN ISRAEL'S LABOR PARTY VOTE

JERUSALEM — A divided Labor Party voted Monday for a leader in a contest that could send Prime Minister Ehud Olmert's ruling coalition veering to the hawkish right, or threaten his political survival.

Exit polls indicated the race between former Prime Minister Ehud Barak and a political newcomer was too close to call — and neither man had enough votes to avoid a runoff.

Ami Ayalon, a dovish former internal security agency head, has pledged to lead the centrist Labor out of its year-old partnership with Olmert if the prime minister's Kadima Party doesn't choose a new leader — a move that could force Olmert to co-opt lawmakers from other parties who take a hard line toward the Palestinians, or renew pressure on him to resign.

Barak says he would serve in an Olmert government, while working within parliament to topple the Israeli leader and call early elections.

A Channel Two television poll declared Ayalon, a former navy admiral and head of Israel's Shin Bet security agency, the winner, while an Israel TV poll said Barak received the most votes. Both polls, however, showed the men falling short of the 40 percent threshold needed to avoid a runoff.

CALIF. EFFORTS HELP INMATE SUICIDE RATE DROP

FOLSOM, Calif. — Every 30 minutes, day and night, guards walk the tiers of the isolation unit at California State Prison, Sacramento, checking inmates to make sure they don't kill themselves.

The guards have been doing so since October, when the prison system instituted a series of reforms to cut the high rate of inmate suicides. The steps were prompted by a federal judge's finding that a disproportionate number of suicides occurred in the isolation cells used to segregate inmates for disciplinary or other reasons.

The measures, which include screening inmates for potential suicidal tendencies and training guards how to intervene, appear to be making a difference.

Guards have reported preventing more than 60 suicides in segregation cells so far this year — out of more than 170 suicides attempted during the past five months in the state's 33 adult prisons.

"They've approached several guys who have nooses around their necks, and they've intervened. They've saved them," said Correctional Capt. Gene Nies, who oversees the Folsom prison's segregation unit. "They know these guys. They start to recognize the signs. They know to check on them more frequently."

STUDY: STAPH INFECTIONS RISING IN CHICAGO NEIGHBORHOODS

CHICAGO — Drug-resistant staph infections have spread to the urban poor, rising almost seven-fold in recent years in some Chicago neighborhoods, a new study finds.

Researchers said the crowded living conditions of public housing and jails may speed up the person-to-person spread of infection.

Called methicillin-resistant staphylococcus aureus, or MRSA, these staph germs can cause skin infections that in rare cases have led to pneumonia, bloodstream infections and a painful, flesh-destroying condition. MRSA is hard to treat because the bacteria have developed resistance to the penicillin drug family.

From 2000 to 2005, the infection rate seen in patients seeking care at Chicago's main public hospital and its affiliated clinics climbed from 24 cases per 100,000 to 164 cases per 100,000, the study found.

Public housing could be a bridge between high-risk people, the researchers wrote in their study, which appears in Monday's Archives of Internal Medicine.

Dr. Susan Gerber of Chicago's Department of Public Health said it would be a mistake to assume the infection isn't also in affluent neighborhoods. The study looked only at people using the public hospital system. The infection rate in the general population is unknown.

TV NETWORKS BRAINSTORM WAYS FOR ADS TO BE SEEN

NEW YORK — Some of the most creative thinking in television these days has nothing to do with comedy or drama. It's about the commercials. Fueled by a growing sense of desperation, networks are inserting games, quizzes and mini-dramas into commercial breaks.

They're incorporating more product pitches into programming. Two experimental programs without traditional commercial breaks will premiere this fall. NBC has even called on Jerry Seinfeld for help.

This is all being done to stop viewers with DVRs from fast-forwarding through advertisements, or to circumvent those that do.

Adding to the urgency, this week Nielsen Media Research begins offering ratings for commercial breaks, instead of just the shows around them.

"We all need to become more creative in how we incorporate sponsors into a program," said Ed Swindler, executive vice president for NBC Universal ad sales. "No one on the creative side or the business side wants to make commercials intrusive, but we do need to commercialize efficiently so viewers can afford to get free television."

MAN WRESTLES WILD LEOPARD THAT JUMPED INTO BED

JERUSALEM — A man clad only in underwear and a T-shirt wrestled a wild leopard to the floor and pinned it for 20 minutes after the cat leapt through a window of his home and hopped into bed with his sleeping family.

"This kind of thing doesn't happen every day," said 49-year-old Arthur Du Mosch, a nature guide. "I don't know why I did it. I wasn't thinking, I just acted."

Raviv Shapira, who heads the southern district of the Israel Nature and Parks Protection Authority, said a half dozen leopards have been spotted recently near Du Mosch's small community of Kibbutz Sde Boker in the Negev desert in southern Israel, although they rarely threaten humans.

Shapira said it was probably food that lured the big cat. Leopards living near humans are usually too old to hunt in the wild and resort to chasing down domestic dogs and cats for food, he added.