Chicago (CNN) — Two additional suspects faced charges in connection with an alleged terror plot in Chicago as world leaders met at a NATO summit there Sunday.

Sebastian Senakiewicz, 24, is charged with falsely making a terrorist threat. Mark Neiweem, 28, is charged with attempted possession of explosives or incendiary devices, prosecutors said in a statement. The men, both believed to be from the city, were scheduled to appear in court at noon Sunday (1 p.m. ET).

Meanwhile, 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 at the summit.

Against a backdrop of massive protests — including the foiled, homegrown terror plot that allegedly 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.

Two senior U.S. officials said NATO leaders would agree Sunday to purchase shared surveillance drones as part of “smart defense,” a term used to describe efforts to do more with less at a time when many nations’ defense budgets are being slashed. Thirteen countries will buy the drones, while other NATO members will help with logistics and data analysis, the officials said.

Security is expected to be tight at the summit following Saturday’s 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. Prosecutors did not detail accusations against the two men charged in connection with the plot Sunday.

Police insist there are no imminent threats to the leaders of more than 50 nations gathering at the 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.

A small contingent of British forces could remain after NATO forces leave in 2014, a senior British official said. A senior U.S. official said the United Kingdom may keep some troops in Afghanistan post-2014 for counter-terrorism purposes. Both officials requested anonymity because they were not authorized to speak to the media.

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.

Speaking to CNN’s “State of the Union” before the start of Sunday’s session, NATO Secretary General Anders Fogh Rasmussen said, “I am optimistic about fund-raising for the Afghan security forces, because at the end of the day, it is less expensive to finance the Afghan security forces to do the combat than to deploy our own troops.”

France’s new president, Francois Hollande, is widely expected to announce the withdrawal of French troops from Afghanistan by year’s end.

A Taliban spokesman said Sunday that Hollande’s declaration “is a decision based on realities and a reflection of the opinion of (his) nation.”

“We call upon all the other NATO member countries to avoid working for the political interests of American officials and answer the call of your own people by immediately removing all your troops from Afghanistan,” Taliban spokesman Zabiullah Mujahid said in a statement, describing what he said was the “savagery” of troops in Afghanistan.

“The invasion of Afghanistan by America and its allies under the banner of ‘war of terror’ was an unjustified and tyrannical action which was only carried out for political and economical gains,” he said.

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.

U.S. Republican presidential frontrunner Mitt Romney was not at the summit, but he weighed in Sunday with an op-ed piece in the Chicago Tribune, arguing that many NATO countries have not contributed enough to the alliance. The Obama administration’s defense budget cuts have further fueled the problem, he said.

“The administration’s irresponsible defense cuts are clearing the way for our partners to do even less,” Romney wrote. “An alliance not undergirded by military strength and U.S. leadership may soon become an alliance in name only.”

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 a 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.