Eight Afghan police were killed Wednesday when Taliban attacked their checkpoint in a brazen assault likely to raise fresh security questions as the United States prepares a troop drawdown. The attack in Ghazni province\'s Qarabagh district, about 120 kilometres (75 miles) southwest of Kabul, is thought to have been an inside job in which insurgents worked with a policeman at the checkpoint to strike. \"The attack started at around 7:00 am (2:30 GMT) and six police officers were killed during a gunfight with the attackers,\" Sayed Amir Shah, the head of Afghanistan\'s intelligence agency in Ghazni province, told AFP. He later said the toll had risen to eight and the fighting had stopped. Mohammad Ali Ahmadi, the deputy provincial governor of Ghazni, confirmed the number of dead. He added: \"Probably one of the police officers at the checkpoint had a previous deal with the insurgents and cooperated with and facilitated the assault.\" The Taliban claimed responsibility for the attack in a text message sent to AFP. Earlier this month, three police were killed in a similar insurgent strike on their checkpoint in the same district. The assault came just hours before President Barack Obama is to use a prime time speech to order a US troop drawdown from Afghanistan, which one official said would likely see 10,000 soldiers back in the United States this year. Obama will stick with his vow to begin pulling out US forces after an 18-month troop surge, but apparently heed Pentagon warnings that an overly swift withdrawal could imperil hard-won gains against the Taliban. A senior defence official said on condition of anonymity that the president would \"likely\" order the return of about 5,000 troops this summer and 5,000 more by the end of the year. Another 20,000 troops, part of a 30,000-strong surge ordered in December 2009, would be withdrawn by the end of next year, meaning elevated force levels would remain through two more Afghan summer fighting seasons. It would still leave more American troops in Afghanistan than when Obama was elected to office in November 2008. But war sceptics argue that after the deaths of more than 1,600 US service personnel and at a cost of nearly $10 billion a month, the American commitment is unsustainable at its present size of 90,000 US troops. There are currently around 130,000 international troops in Afghanistan under the NATO-led International Security Assistance Force (ISAF) including some 90,000 from the United States. All foreign combat troops are due to leave Afghanistan by the end of 2014, with a limited withdrawal expected to begin next month. The transition process will hand increasing responsibility for security to the Afghan police and army despite questions from some experts over whether they are ready to step into the breach.