Kabul ? The top U.S. military officer said Tuesday that he’s confident that most of the 30,000 additional troops that are being sent to Afghanistan will be there by August.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, told reporters traveling with him in Afghanistan that the first 16,000 troops who already have orders will be in on schedule.

On Monday, Lt. Gen. David Rodriguez, the second-highest ranking U.S. general in Afghanistan, said the rapid escalation of American troops would take longer than expected, possibly as long as 11 months. Rodriguez blamed the delay on the logistical challenges the military faces in bringing in so many forces so quickly.

But Mullen said that he’s “reasonably confident” the logistics can be made to work, although “I want a plan B because life doesn’t always work out.”

He said the vast majority of troops in the surge ordered by President Barack Obama should be in Afghanistan by August.