KABUL, Afghanistan - Facing an intensified Taliban insurgency, Afghan President Ashraf Ghani plans to fire senior civilian and military leaders in the country's most volatile provinces to reinvigorate the battle against militants, officials have told The Associated Press.

With Afghan security forces suffering high casualties in the run-up to the official Dec. 31 end of the U.S. and NATO combat mission, the newly elected president is eager to chart a new course. But the question remains what effect the shake-up will ultimately have in a war-torn country mired in corruption and riven by complex ethnic and tribal rivalries.

"Ghani feels there is a need for reform within the armed forces," said Franz-Michael Mellbin, the special representative in Afghanistan for the European Union. "There is an inherent weakness in the way the armed forces have been managing their personnel that didn't allow the best and brightest to step forward."

Ghani plans to replace officials in the northern provinces of Kunduz and Baghdis, Ghazni and Nangahar provinces in the east bordering Pakistan and Helmand in the south, presidential spokesman Nazifullah Salarzai told the AP.

The provincial sweep will roll out over the next two to three months and will begin soon, he said.

"Senior government officials will be replaced," Salarzai said.

Areas of all five provinces have been under Taliban control for years and security forces have suffered record-high casualties as they come under regular attack by insurgents. A Nov. 23 suicide bombing at a volleyball tournament in eastern Paktika province killed at least 50 people, making it Afghanistan's deadliest terror attack this year.

The attacks put pressure on Ghani's new administration, which earlier this month ordered a top-to-bottom review of the country's military and security strategy. The review, which officials say will examine everything from battlefield strategy to the rules of engagement for Afghan security forces, is expected to be completed within six months.

One major resignation came Sunday when Kabul police chief Gen. Mohammad Zahir stepped down following a string of attacks in the capital over three days that killed four foreigners - including an employee of the British embassy - and several Afghan civilians. On Monday, however, police spokesman Obidullah, who goes by one name like many Afghans, said that the Interior Ministry rejected Zahir's resignation.

Already, Ghani has signed a bilateral security agreement with Washington and a status of forces agreement with NATO that his predecessor Hamid Karzai declined to sign. U.S. President Barack Obama also has approved an expanded combat mission authorizing American troops to engage Taliban insurgents - not just al-Qaida - and to provide air support when needed.

Still, Afghanistan faces a looming challenge as U.S. forces will be reduced to 9,800 by the end of this year, a figure expected to be cut in half by the end of 2015 before a planned complete withdrawal at the end of 2016.

Ghani left Monday for Brussels, where he will meet with NATO Secretary-General Jens Stoltenberg and the foreign ministers of NATO countries. He later will travel to London for a crucial conference to showcase his administration's first efforts to reform the country.

But Ghani's security push also may have had an unintended consequence. Moderate members of the Taliban that Ghani himself hoped to negotiate with may have been sidelined because of it, political analyst Wahid Mozhda said.

"Those we call the moderate Taliban have lost that hope," Mozhda said. "More extremist leaders have taken over and believe that war is their only option."