U.S. Marine Gen. Joseph Dunford said progress toward a secure and stable country is "indisputable," Khaama Press reported.
"Some basic facts highlight the improved security across the country,' said Dunford. Who leads the International Security Assistance Force.
He cited as evidence steady gains by the Afghan military and police forces in confidence, competence and commitment.
His comments came amid reports that attacks by Taliban militants increased 47 percent in the first three months of 2013.
The United Nations says civilian casualties increased almost 30 percent in the first quarter of the year compared to the same period last year.
Afghan security forces on Thursday arrested at least eight Taliban fighters from Pakistan in southern Kandahar province, local authorities said.
The militants had been sent to suppress anti-Taliban groups, said Panjwai district governor Haji Fazal Ahmad.
In a separate incident, one Afghan police officer was injured in Panjwai district when militants attacked security forces eradicating opium fields.