The United States, its European allies and the Afghan government have coalesced around a plan to spend about $4.1 billion a year on Afghan army and police forces. (Johannes Eisele/AFP/Getty Images)

Senior Obama administration officials, faced with stepped-up enemy attacks in Kabul and war weariness at home, pledged a long-term commitment to Afghanistan on Wednesday and said their strategy to end the U.S. combat role by the end of 2014 remains on track.

Defense Secretary Leon E. Panetta and Secretary of State Hillary Rodham Clinton took part Wednesday in the last high-level meeting of the NATO allies before a key summit next month in Chicago that administration officials hope will finalize the United States’ and NATO’s relationship with Afghanistan after 2014. A critical part of that partnership is a commitment by Washington and its allies to fund the cash-strapped Afghan government’s security forces.

The United States and its allies have generally agreed to spend about $4.1 billion a year on Afghan army and police forces after combat operations end in late 2014.

“History proves that insurgencies are best and ultimately defeated not by foreign troops but by indigenous forces,” Panetta told reporters. “When the Afghans do their job, we are doing our job. When the Afghans win, we win.”

The money would pay for a force of about 230,000 Afghan army and police officers, significantly fewer than in a long-standing plan to increase the forces to about 350,000 by this fall. Although U.S. officials said attack levels in Afghanistan are falling, Taliban insurgents still have the ability to carry out large-scale coordinated assaults throughout the country. This week, insurgents made coordinated attacks in Kabul and two provinces.

Clinton, who appeared at a news conference alongside Panetta, was quick to point out that Afghan forces played the leading role in repelling the assaults.

“As difficult a week as this has been in Kabul and other parts of Afghanistan, the big picture is clear,” she said. “The campaign plan is on track. . . . The attacks in Kabul show us that while the threat remains real, the transition can work.”

The United States and its Afghan allies have not abandoned the plan to build the larger 350,000-member force, which is needed to cover the withdrawal of American and NATO troops in 2013 and 2014, officials said. But the larger force, which would cost about $6 billion annually, is not seen as affordable over the long term in a country with a weak economy and little governance.

The discussions about the size and makeup of the Afghan security forces are a key part of the meetings among senior military and diplomatic officials in Brussels this week. The officials gathered to finalize plans to end NATO’s combat mission in Afghanistan and turn over responsibility to the government in Kabul.

No firm decisions have been made on how quickly to shrink the Afghan security forces after combat operations end. U.S. officials said the size of the army and police force will be determined by the strength of the Taliban insurgency, but the consensus surrounding the $4.1 billion figure seems to have been driven as much by financial considerations as by conditions on the ground.

The current plans call for the United States to spend about $2.2 billion a year on the Afghan forces after 2014, down from the $5.7 billion it will spend for the larger force in 2013. America’s allies are expected to contribute about $1.3 billion a year after 2014.

“We will play our part and pay our share in sustaining Afghan security forces at the right level in the years to come so they can keep their country strong and secure,” said NATO Secretary General Anders Fogh Rasmussen.

The Afghan government, which will kick in about $500 million a year for its security forces, has expressed deep concern in recent days about the West’s willingness to keep paying for Afghan army and police forces after combat operations have ended and most U.S. troops have gone home.

President Hamid Karzai, whose corruption-plagued government faces a resilient insurgency, suggested Tuesday that any long-term security pact between the United States and Afghanistan should include a commitment by Washington to spend $2 billion annually on the Afghan forces.

Clinton and Panetta ruled out putting such a pledge in writing but sought to allay the Afghan president’s concerns that the United States will abandon his country as its combat troops depart.

“We do not have the power to lock in money,” Panetta said, noting that Congress must approve any disbursement of U.S. funds annually.

Several NATO allies made long-term pledges in Brussels to support Afghan troops after 2014.

“We will have the resources necessary to protect the Afghan state and the Afghan people,” Clinton said. “Both Leon and I were encouraged and believe we are making progress.”

Other U.S. officials said Karzai had moderated his demands for a written $2 billion pledge from the United States before the Chicago meeting. Obama administration officials have been working for months to ensure that the details of a long-term relationship with the Afghan government can be announced in Chicago.