From Elise Labott and Mike Mount, CNN
CHICAGO (CNN) - The road map out of the war in Afghanistan is expected to be drawn up by U.S. President Barack Obama and other world leaders when they gather Sunday at the NATO summit in Chicago.
Against a backdrop of massive protests -- and a foiled, homegrown terror plot that targeted Obama and others -- the summit will open with NATO countries trying to figure out how to meet a 2014 withdrawal from an unpopular war while shoring up Afghanistan's security forces.
Security is expected to be tight at the summit following the arrest of three men, described by authorities as anarchists who plotted to attack Obama's Chicago campaign headquarters and lob Molotov cocktails at police during the summit.
Police insist there are no imminent threats to the leaders of more than 50 nations gathering at the summit. [RELATED: Bail set at $1.5 million bail each for 3 accused of planning terror at NATO summit]
The leaders are expected to formally adopt a timetable to transition security from the NATO-led International Security Assistance Force to Afghan forces, senior administration officials told CNN.
The officials, speaking on condition of anonymity as a matter of practice, said the plan will also lay out NATO's training and advisory role after 2014.
One of the key issues to be considered by the NATO leaders is who will pay for the buildup of Afghan forces as ISAF draws down its troops. Afghan security forces are expected to total 350,000 by 2015, according to CNN National Security Analyst Peter Bergen.
Afghan President Hamid Karzai, who is attending the summit along with Pakistani President Asif Ali Zardari, can only afford to cover a fraction of the cost of building up his country's forces. The cost of building up forces is expected to total roughly $4 billion annually by 2014, Bergen said.
France's new president, Francois Hollande, is widely expected to announce the withdrawal of French troops from Afghanistan by year's end.
Also, at issue at the NATO summit, is Islamabad's continued blockade of much-needed NATO supplies shipped over Pakistani roads to Afghanistan.
Pakistan closed the ground routes after a NATO airstrike in November killed two dozen of its soldiers. NATO insists the incident was an accident.
The United States and NATO are unlikely to reach an agreement with Pakistan at the summit, according to two senior U.S. officials, who spoke on condition of anonymity because they were not authorized to speak on the subject.
"There is no deal, and there won't be one until President Zardari returns" to Pakistan, one of the officials said. "And even that is not assured."
The goal, says the official, "is to get a deal. It's less important as to when."
Without a deal, the officials said Obama would not meet with Zardari at the summit. The two are scheduled to hold trilateral talks with Karzai on political reconciliation in Afghanistan. Pakistan's support in reaching a deal with the Taliban is seen as critical in ending the war in Afghanistan.
Outside the summit, Chicago authorities expect to have their hands full with protests.
On Saturday, the eve of the summit, Occupy Chicago protesters accused police of running down one of their own with a patrol van. A video, posted online by a protester and picked up by news organization, appeared to show the van bumping a protestor.
But a spokesman for Chicago Mayor Rahm Emmanuel said the driver of the van was responding to an attack by the protester.
"The individual was attacking the van and trying to slash tires on it with a knife as the van was moving slowly through a crowd," spokesman Bill McCaffrey told CNN.
He said the person successfully slashed the tires, and then fled.
CNN's Greg Morrison and Chelsea J. Carter contributed to this report.