Violence spiked in southern Afghanistan where militants stormed a NATO military base and attacked a police checkpoint, while a U.S. service member was killed by gunmen wearing Afghan security force uniforms and eight civilians died in a roadside bomb explosion, authorities said Tuesday.
The heaviest fighting in Afghanistan this summer is in the south and east where Afghan forces are increasingly taking charge of security from their international partners.
Much of the violence over the two days has been in Kandahar province, the Taliban's birthplace in the south.
On Monday, individuals dressed in Afghan police uniforms turned their guns on their U.S. partners, leaving one American service member dead and nine other U.S. troops injured, U.S. officials said. They spoke on condition of anonymity to discuss the incident in Zhari district, which is still under investigation.
It was the latest in a rising number of cases where Afghan security forces, or militants disguised in their uniforms, have killed their international partners.
Efforts to draw down the number of U.S. troops in Afghanistan rely on the Americans working closely with their Afghan partners to train and mentor them so that they can take over the security of their country. Such insider attacks fuel distrust between the two forces and have triggered increased security protections for the U.S. service members serving in Afghanistan.
It remains unclear whether the three gunmen were actual members of the Afghan National Police or were militants dressed in their uniforms.
The number of insider attacks in the country has escalated, with more than a dozen fatal assaults already this year, that have led to more than 20 deaths.
Last year there were a total of 21 fatal attacks that killed 35 coalition service members, according to the coalition. That compares with 11 fatal attacks and 20 deaths the previous year. In 2007 and 2008 there were a combined total of four attacks and four deaths.
The increase accelerated after a series of mistakes and other behavioral problems by U.S. troops serving in Afghanistan, including the burning of Qurans and other religious materials earlier this year at a U.S. base north of Kabul.
Early Tuesday, militants stormed a NATO base in another part of Kandahar province.
The Taliban claimed responsibility for the attack and said they were attempting to target the base's sleeping areas for troops.
"Initial reports indicate that seven insurgents launched an attack on a NATO installation and initially were successful in breaching the outer security perimeter," NATO said in a statement. "Current reporting indicates all the attackers have been killed."
The coalition said no NATO service members died in the pre-dawn attack in Shah Wali Kot district.
Javid Faisal, a spokesman for Kandahar province, said initial reporting indicated that at least one foreign worker was killed and two other foreigners were wounded, but this could not be independently confirmed.
A few hours later, militants attacked a police checkpoint in Kandahar city. Three policemen were killed and nine others were injured during an hour-long gun battle that ensued, according to the Ministry of Interior. Four militants also died in the incident.
The Taliban again claimed responsibility and said the clash lasted six hours.
In neighboring Helmand province, a roadside bomb exploded on Monday, killing eight civilians, including women and children. The civilians were driving in Musa Qala district when their car hit the mine, the governor's office said in a statement issued on Tuesday.
According to the United Nations, 579 civilians were killed in the first four months of this year. The Taliban and other anti-government forces caused 79 percent of all civilian casualties and Afghan and foreign forces 9 percent. It was not clear who was responsible for the remaining 12 percent of the casualties.
Elsewhere in Afghanistan, gunmen on Tuesday morning assassinated two individuals employed by the local government in Chaparhar district of Nangarhar province in eastern Afghanistan, said the governor's spokesman, Ahmad Zia Abdulzai. The Taliban routinely target Afghan officials in an attempt to weaken the resolve of a government they say is collaborating with foreign occupiers.
Also on Tuesday, Afghan authorities in Kabul announced that two men have been charged in connection with a suicide bombing that killed 56 worshippers and wounded more than 160 others last year outside a Shiite shrine in Kabul. The massive attack on Dec. 6, which left behind a grisly scene of bodies and blood, was Afghanistan's first major sectarian assault since the fall of the Taliban regime more than a decade ago.
Officials with the Afghan intelligence service and Attorney General Mohammed Ishaq Aloko said at a news conference that the two men confessed to transporting the suicide attacker from Peshawar, a city in northwest Pakistan, to the shrine in Kabul.
Lashkar-e-Jhangvi, a Pakistan-based group that has carried out other attacks against Shiite Muslims, claimed responsibility for the bombing.
The attorney general said the bombing was an attempt to create division between Afghan Sunni and Shia Muslims. He alleged that the Pakistani intelligence service was involved in the attack during the period of Ashoura, which marks the death of Imam Hussein, a grandson of the Prophet Muhammad, in 680 A.D.
"Maybe Lashkar-e-Jhangvi was behind it," Aloko said. But he said that regardless of who conducted the attack, it was supported by the intelligence agencies of the neighboring countries. When he was asked which neighboring country, Aloko said: "The attack was planned and organized in Peshawar and executed on the holy day."
Pakistan has repeatedly denied Afghan officials' allegations that it facilitates attacks in Afghanistan.
One of the men, Rahim Gul from Bati Kot district of Nangarhar province, told officials on a taped confession that he transported the suicide bomber because he was poor and badly needed the 10,000 Pakistani rupees (about $106) that the organizers of the plot agreed to pay him. The second man charged, Habibullah, who uses only one name, is from Nangarhar's Surkh Rod district.
"I made a big mistake," Habibullah said on a video disc the intelligence service distributed to reporters.
Associated Press Writers Mirwais Khan in Kandahar and Rahim Faiez and Amir Shah in Kabul contributed to this report.