LONDON — In the homestretch of a 41-year U.S. Army career shaped by war and the scars of war, Gen. Martin Dempsey sounds unconvinced that Iraq has found its path to lasting victory over the Islamic State group.

But neither does the top military adviser to President Obama say the threats to Iraq today justify sending American ground troops back into combat.

He counsels patience, for now.

Give the Iraqis more time to heal their internal divisions and fight their own battles. Resist the temptation to grab control of the contest against the Islamic State group. An enduring victory will take more than military might; it will require a unified Iraq supported by neighbors.

"If we were to take control of this campaign, I mean literally seize control of the campaign, then there's no doubt in my mind we would probably defeat ISIL on, let's say, a faster timeline, but at some considerable cost to our young men and women in uniform," he told U.S. troops Thursday in an aircraft hangar in Naples, Italy, on one of his last overseas trips before finishing his four-year tenure as chairman of the Joint Chiefs of Staff.

And that defeat would not last.

"Maybe ISIL goes away, maybe they're defeated militarily, and two years from now another group with another name and another ideology ... will just be back," he said earlier that day, using an alternative acronym for the militants who occupy large parts of Iraq and Syria.

"So this campaign is built on the premise that it has to be won by our coalition partners and by the Iraqis themselves. That's a baseline assumption. If that assumption changes I'll go to work on Plan B."

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It's an assessment based on Dempsey's decades of experience in the Middle East.

After the Sept. 11 attacks, he served in Saudi Arabia as an adviser on internal defense. He led the U.S. Army's 1st Armored Division in combat in Iraq in 2003-04, commanded the U.S. training mission in Baghdad in 2005-07, oversaw military operations in the greater Middle East as acting commander of U.S. Central Command in 2008, and as Joint Chiefs chairman has been the chief military adviser to President Barack Obama and his National Security Council.

Dempsey's assessment also reflects scars of his wartime experience. On his desk in the Pentagon sits a small wooden box of laminated cards, one for each of the more than 100 soldiers who died in Iraq under his command in 2003-04. Carved on the box's lid are the words, "Make it matter."

His Iraq view, however, is not shared by some in Congress, and others, who say the U.S. cannot afford to count on the Iraqis. U.S. Rep. Mac Thornberry, R-Texas, chairman of the House Armed Services Committee, calls Obama's approach too passive and lacking strategic coherence. Thornberry's committee has called Dempsey and U.S. Defense Secretary Ash Carter to testify Wednesday on the administration's Middle East policy.

The Obama administration clearly has its own doubts about Iraq's progress. This past week the White House announced the U.S. would send up to 450 troops to a new base in Anbar province, mainly to advise the Iraqis on planning and execution of a counteroffensive to retake Ramadi, the provincial capital. On Thursday, Dempsey said more such U.S. hubs could be opened elsewhere in Iraq as the campaign advances.

Dempsey is leery of deeper U.S. military involvement to help the Iraqis because "that discourages, at some level, them from really getting serious about restoring their own security." It's a wariness shared by Obama, who said last August that he would not allow the U.S. to "get dragged into another war in Iraq."

Dempsey knows Iraq and its political weaknesses better than most. While he is willing to give the Shiite-dominated government in Baghdad more time to achieve political reconciliation with the Sunnis, he does not sound overly optimistic.

"We have not given up on the possibility that the Iraqi government can actually be whole," he said.

He was alluding to lethal fissures between Iraq's Sunnis and Shiites. They worsened after the 2003 U.S. invasion that toppled Saddam Hussein and then returned during the tenure of Nouri al-Maliki as prime minister.

The Obama administration had high hopes that al-Maliki's successor, Haider al-Abadi, would advance reconciliation when he assumed office last September, but he has yet to deliver.

Dempsey also has considered alternative courses of U.S. action should the Iraqis prove incapable of producing what he called "game changers," meaning moves such as passing legislation to create a "national guard" of Sunni tribal fighters.

"Then we will have to look for other avenues to maintain pressure on ISIL and find other partners who can ensure that we can protect ourselves," he said, describing what sounds like a counterterrorism campaign not necessarily aimed at restoring the Iraq-Syria border erased by IS.

"If ISIL begins to threaten our persons, our facilities, our national interests — if they begin conducting external planning, plots against the (U.S.) homeland, for example — we've got (military) capabilities in the neighborhood we can bring to bear. ... But at this point I just don't think we should be giving up on the government of Iraq and its ability to conduct this campaign, with our help, without (the U.S.) taking it over."