-- A U.S. service member has died from wounds sustained today in an operation near Lashkar Gah in Helmand province in Afghanistan, the Pentagon confirmed.
Another U.S. service member and six Afghan soldiers sustained wounds during the operation.
"On behalf of all of U.S. Forces Afghanistan as well as Resolute Support, our deepest sympathies go out to the families and friends of those involved," Gen. John W. Nicholson, the commander of U.S. Forces Afghanistan and Resolute Support, said in the news release. "We are deeply saddened by this loss but remain committed to helping our Afghan partners provide a brighter future for themselves and their children."
The Pentagon confirmed Monday that 100 U.S. troops were sent to Lashkar Gah to train, advise and assist local Afghan police as they face a major summer offensive by the Taliban. That group includes trainers as well as a force to provide protection for them.
When pressed on the progress made in Helmand, Cook said that the Afghan forces have shown "resiliency" in recent months and that the decision to send additional U.S. forces to Lashkar Gah reflected U.S. support.
But he warned, "There still are challenges in Afghanistan."
"There are going to be setbacks along the way," Cook said. "Certainly, there's room for improvement."
ABC News’ Luis Martinez contributed to this report.