WASHINGTON — The Army’s top general said yesterday that lengthening American tours of duty in Iraq and Afghanistan beyond the current 15 months would be too stressful and risky for troops.

General George Casey also said he didn’t know when officials would be able to cut the length of soldiers’ tours back to 12 months. “I don’t see going beyond the 15 months,” General Casey said. “I’ve been there in Iraq, I’ve watched the nature of the combat and the stresses and strains that it puts on these soldiers.” He said the 90-day extension ordered by officials earlier this year can go quickly.

“Any more than that, it puts our soldiers at a level of stress and a level of risk that right now I’m not comfortable with,” he told reporters in an appearance at the National Press Club. “So it would be very hard for me to recommend going beyond the 15 months and … we want to get down from 15 months as quickly as we can.”

The Army’s vice chief of staff, General Richard Cody, said earlier yesterday that troops may be facing the longer deployments at least until next June. General Cody said officials are assessing the question, but it would take at least until then to return average deployments to 12 months while maintaining the roughly 160,000 troops in Iraq.

“It’s going to take awhile to get off the 15 months,” he said in an interview with the Associated Press at Fort Hood, Texas.