Afghanistan's police are regularly attacked
Suspected militants have killed at least 16 policemen in two attacks in Afghanistan, officials say.
Gunmen targeted police posts in Baghlan province in the north and in Helmand province in the south. In each ambush eight policemen were killed.
The police in Afghanistan have often been targets of militants and have suffered much heavier casualties than foreign troops.
Meanwhile, the top US military officer has arrived in Afghanistan for talks.
Joint Chiefs of Staff Adm Mike Mullen is expected to hold a series of meetings with government officials.
Adm Mullen's visit comes even as the first of 30,000 American troops are getting ready to arrive in Afghanistan.
In both incidents, police checkpoints came under attack in the middle of the night.
The attack in Baghlan - which has seen a marked rise in violence this year - occurred on a main highway from the capital, Kabul.
"The policemen who were killed in the attack were on duty to provide security for the military convoys and local people in the main highway in Baghlan province," provincial governor Mohammad Akbar Barakzai told the Associated Press news agency.
One report said two militants were also killed in the ambush early on Monday.
At about the same time a police checkpoint was attacked in Lashkar Gah, the capital of Helmand province.
The Taliban called the BBC to say they carried out the attack.
Both checkpoints are now back under the control of the security forces.
The BBC's Ian Pannell in Kabul says insurgents in Afghanistan have targeted those regarded as working with the government.
He says the police have borne the brunt of losses - with hundreds killed in the past few years.