WASHINGTON - At a key juncture in the Iraq war, the military chiefs conveyed to President Bush yesterday their concern about a growing strain on U.S. forces and their families from long and repeated combat tours.

Bush met privately at the Pentagon with the Joint Chiefs of Staff and Defense Secretary Robert Gates in preparation for decisions about how long to sustain the U.S. buildup in Iraq, whether to change course this fall and how to save the health of a heavily stressed Army and Marines Corps.

Indications are that Bush intends to stick with his current approach, at least into 2008, despite pressure from the Democratic-led Congress — including some prominent Republicans — to find a new course.

Still to be heard is the long-awaited assessment by Gen. David Petraeus, Bush’s choice to execute the new strategy he announced in January to improve security in Baghdad.

Petraeus did not participate in yesterday’s session, but one U.S. senior official said that Petraeus, along with Ryan Crocker, the U.S. ambassador to Iraq, would probably tell Bush and Congress in mid-September that the buildup had succeeded in allowing slow but sure progress on the military and political fronts.

Petraeus and Crocker will also argue for a continuation of the current policy with some adjustments, said the official, speaking on condition of anonymity because he was discussing internal deliberations.

Bush’s critics speak of mounting evidence that although the buildup may have slowed sectarian violence in Baghdad, the Iraqis are making almost no headway toward political reconciliation.

There are no signs that the Pentagon’s top generals and admirals are pushing for an early end to the war, but they are concerned not only about strains on their forces but also about the possibility that the focus on counterinsurgency warfare in Iraq leaves the military ill-prepared in the event of a crisis elsewhere.

He warns Congress against any effort to withdraw early