As NATO leaders on Sunday night prepared to approve an agreement to train and equip Iraq’s fledgling security forces, violent opposition to the American occupation of Iraq continued with disclosures of the kidnappings of a U.S. Marine and a Pakistani employee of the American contracting firm Halliburton Inc., and with attacks on Baghdad’s airport and city.

Militants threatened to behead the two captives unless prisoners were released from U.S. custody.

Four people also were killed Sunday, including an American soldier at a military camp and the occupant of a military cargo plane hit by small arms fire as it took off from the main Baghdad airport.

Details of the kidnapping of the Marine were sketchy late Sunday. The news network Al-Jazeera reported that members of a “purported Iraqi resistance” group took the Marine hostage.

U.S. military officials in Baghdad confirmed that Marine Cpl. Wassef Ali Hassoun had been missing since June 21, but could not confirm that he was being held hostage. Hassoun was assigned to the 1st Marine Expeditionary Force from Camp Pendleton, Calif. No hometown was released, although a statement describes the Marine as being of Lebanese descent.

A man wearing a Marine uniform and Hassoun’s nametag was pictured on the videotape aired by Al-Jazeera. Military investigators are continuing their inquiry into the disappearance.

Also Sunday, a chilling hostage video surfaced in which militants threatened to behead a Pakistani employee of the Halliburton subsidiary Kellogg, Brown & Root. The insurgents said they would kill the man if American forces didn’t release prisoners held at Abu Ghraib and elsewhere in Iraq within the next three days.

“I’m also Muslim, but despite this they didn’t release me,” the man said on a video broadcast by Arab language television station Al Arabiya. “They are going to cut the head of any person regardless of whether he is a Muslim or not.”

Turkish captives

The kidnappings Sunday follow the capture of three Turkish civilians by followers of Islamic militant Abu Musab al Zarqawi. The group threatened to behead them after 72 hours unless Turkish companies stop doing business with American forces in Iraq. The exact deadline is unclear and could come some time today.

The Zarqawi group has claimed credit for the beheadings of Pennsylvanian Nicholas Berg and South Korean Kim Sun-il.

After a meeting with U.S. Defense Secretary Donald Rumsfeld Sunday in Istanbul, where President Bush was attending a NATO summit, Turkish Defense Minister Vecdi Gonul said Turkey would not consider demands from insurgents who took three Turkish hostages.

“Every day 1,500 or 2,000 trucks are going to Iraq and bring medicine food, everything,” Gonul said. “These things are humanitarian. It is sad to have Turkish people captured by some forces in Iraq. They like to help the Iraqi people.”

This image from a video broadcast by the Aljazeera network shows a man identified as Wassef Ali Hassoun, a U.S. Marine whom Iraqi militants claim to have captured.

NATO summit

In Istanbul, NATO leaders on Sunday night convened their first summit since the Iraq war and prepared to approve an agreement to train and equip Iraq’s fledgling security forces.

White House officials described the anticipated agreement as a significant step after more than a year of deep division within the alliance over the war in Iraq.

But it also represented a serious reduction in expectations by the Bush administration, which had originally hoped NATO countries would be willing to put troops on the ground, as they have in Afghanistan.

The administration official said details including how many forces NATO would train, and how much of that training might occur outside Iraq, was still under discussion.

In recent weeks, Bush administration officials have lowered expectations for the summit, recognizing that NATO allies were unable to commit troops to Iraq because of existing commitments to Afghanistan and opposition in their own countries.

The leaders of NATO’s 26 members met for a formal dinner Sunday night and were scheduled to hold working meetings today and Tuesday — the day before the United States was scheduled to return national sovereignty to Iraq.

Model of democracy

Bush spent the first half of the day with Turkish leaders in the capital, Ankara, where he placed a wreath at the mausoleum of Kemal Ataturk, the founder of the modern, secular Turkish state.

Throughout his visit, the president has praised Turkey as a secular yet Muslim nation, the kind of democracy he hopes other nations, including Iraq, will emulate.

“I appreciate so very much the example your country has set on how to be a Muslim country and at the same time, a country which embraces democracy and rule of law and freedom,” Bush said as he met with Turkish Prime Minister Tayyip Erdogan in Ankara.

Bush administration officials described the summit as marking a new stage in the alliance’s history. Until recently NATO considered its mission of defending Europe and North America to mean it would not act outside those continents.

But nearly three years after the Sept. 11, 2001, attacks, U.S. officials say the alliance now agrees that defending itself means addressing threats that arise outside of its traditional geographic sphere of influence.