Body guards rush Christopher Hill, the U.S. ambassador to Iraq, inside a museum in Mosul last month after gunfire was heard in the distance.

AP

WASHINGTON — A few Sundays ago in Baghdad, Christopher Hill threw a lacrosse ball on the U.S. Embassy grounds with Terry Barnich, an aging player from Georgetown University, vintage 1977, and talked up their scheme to organize a team of exiles in Iraq.

By the next afternoon — just hours after Ambassador Hill presided at Memorial Day ceremonies in the American compound — Barnich was dead. The Chicago businessman, on leave to serve in the State Department, was killed along with two colleagues when their convoy hit a roadside bomb near a public works project in Fallujah.

The ambush, in a key western river port that has come to symbolize Iraq’s return from the brink of civil war, was a hard reminder that the remnants of al-Qaida in Iraq remain intent on disrupting the ambitious timetable for U.S. troops to conclude a combat mission that has lasted for more than six years.

“The gains are very fragile,” Hill said last week during a visit to Washington. “At my age I lose sleep for a lot of reasons, but the capacity of the Iraqi security forces to take over for the best trained fighting force that the world has ever known — yes that would be one of them,” said Hill, who will turn 57 in August.

But he said U.S. officials have looked very hard at the readiness of Iraqi security forces to take the baton from U.S. combat troops. “We believe they are ready now,” declared Hill, so on Tuesday U.S. combat troops will meet their deadline to withdraw from every city and town in Iraq — even the multiethnic northern cauldron of Mosul and Bagdad’s most troubled neighborhoods.

President Obama’s newly installed ambassador spoke between briefings with top officials, including Vice President Joe Biden, on the progress toward the June 30 deadline, which Prime Minister Nouri al-Maliki has declared a national holiday to commemorate a milestone in Iraq’s struggle to build a stable democracy.

During Hill’s brief return to the United States, stepped-up attacks claimed about 200 lives in Iraq — more than 75 in the bombing of a marketplace in Baghdad’s volatile Sadr City and almost as many more in a truck-bombing in Kirkuk, the oil-rich northern city at the center of the tensions between Iraq’s Kurds and Sunni Arabs.

The carnage does not approach the levels of violence that made the war seem a lost cause to many Americans before the U.S. troop surge of 2007. In fact, May brought the lowest monthly toll of Iraqi casualties since the time of the U.S. invasion in 2003.

But the fresh attacks have been grave enough to raise fears about whether Iraqi forces can maintain the relatively peaceful conditions that gave rise to the 2008 pact between the United States and Iraq calling for all the American troops to depart by the end of 2011. After Tuesday, the next great milestone will be the national elections in January. Most of the 130,000 U.S. troops now in Iraq will remain through the year to ensure the security of the elections. Then the U.S. force is slated to shrink rapidly to about 50,000 by August of 2010, followed by complete withdrawal the next year.

Hill depicted the current attacks as intended to sabotage these gains and plunge Iraq’s long-simmering ethnic and religious tensions back into armed strife. While in the United States, Hill, a diplomat’s son who starred on the lacrosse fields of Moses Brown School in Providence and Bowdoin College in Maine, caught the opener of the Red Sox series here against the Washington Nationals and stopped for a day at his home in Little Compton. He visited with daughter Amelia, a recent college graduate who works at a nonprofit organization in Boston, helping low-income homeowners with mortgage problems, and son Nat, a civilian employee of the Defense Department who recently returned from Iraq. (Daughter Clara, a Bowdoin student, is working this summer at the U.S. embassy in Belgrade.)

During an interview in a small park in Foggy Bottom, Hill spoke of solid prospects for success in Iraq, but he did so with a careful balance of hopes and fears born of his early reading of the situation there, and his 32 years of experience in assignments from post-Cold War Poland and the Balkan states at war in the late 1990s, to the tense multilateral talks over North Korea’s nuclear program during the past few years.

Hill described some early encounters in the job he assumed only weeks ago, after the Senate voted to confirm him as President Obama’s nominee to one of the most challenging jobs in the Foreign Service.

Among the most portentous was a visit in mid-May to Mosul, a strategically located trading city where the tensions between independent-minded Kurds and Sunni Muslim Arabs were only too evident — as were the continuing efforts of insurgents to exacerbate them with violent attacks.

Hill met a delegation of Kurdish provincial officials at the city’s heavily fortified airport — “closer to Mosul than T.H. Green is to Providence,” he said — and heard firsthand of discord that is echoed elsewhere in the north in disputes over provincial borders and rights to the region’s oil riches.

In Mosul proper, there was a spooky moment as Hill exited his mine-resistant armored vehicle to walk to a meeting with local Sunni leaders in a museum of archaeological treasures from ancient Assyria. A uniformed Iraqi inadvertently — and harmlessly — fired a machine gun burst that prompted the ambassador’s security guards to hustle his party into the museum. “As Tip O’Neill once observed, all politics is local, and in that part of the world all ethnic disputes seem to be local, so you have to understand what goes on in all the various communities,” Hill said. “It’s something I did a lot of in the Balkans. I don’t claim to have any special insights, but I certainly have dealt with similar issues. I certainly know the right questions to ask. And I certainly know when to shut up and listen.”

Possibly the most important — and intransigent — debate across Iraq and in the semiautonomous Kurdish region beyond Mosul is how to fairly distribute Iraq’s vast oil riches. A long-sought series of legal and parliamentary agreements on oil remains elusive. But Hill said he has met with all the major players in an interim measure that coincides with the troop-withdrawal milestone: this week’s international auction of contract rights to assist Iraq in modernizing production at its existing oil fields.

“Iraq is sitting on an awful lot of oil but to date it has not been taken out of the ground very efficiently,” Hill explained. “The injection of international know-how and international technology and international capitol, I think, would be very helpful to the Iraqis,” he said, so he has made it his business to meet with the top Iraqi leaders involved in the auction — as well as officials of Exxon and Chevron, the U.S. oil giants interested in the auction.

“The fact that we are talking about oil lease auctions and not about indirect fire attacks on the Green Zone [which houses the U.S. Embassy and the Iraqi government headquarters] is indeed a good sign,” Hill observed dryly. He also struck a characteristic note of caution about the still-limited capacity of Iraq’s government ministries to serve the people.

After the remarkable outbreak of peace over the past two years in battle-ravaged Fallujah, the roadside bombing of the public works convoy on May 25 was especially galling.

“These people were there for the sole reason of helping Iraqis. To be blown up as they were is just inexplicable,” said Hill. But the ambassador quickly moved on to reprise the message of his speech at the embassy earlier that Memorial Day morning: the enterprise in Iraq must be completed with the war dead in mind, “to assure that their sacrifice was not in vain.”

jmulligan@belo-dc.com