CHICAGO (CNN) -- World leaders huddling in high-stakes, back-to-back summits this weekend will tackle the European economic crisis and the future of the Afghan war
The diplomatic marathon started Friday, when Group of Eight leaders began its two-day meeting at President Barack Obama's Camp David retreat in Maryland. On Sunday, NATO kicks off its two-day summit in Chicago.
The G8 -- comprising the United States, France, the United Kingdom, Germany, Japan, Italy, Canada and Russia -- is expected center on whether an economically weakened, debt-laden Europe should continue down the road of massive deficit cuts trumpeted by German Chancellor Angela Merkel or focus more on economic stimulus to help the continent grow its way out of the current crisis.
Hanging over the deliberations is the fate of economically battered Greece, which has been unable to form an elected government. Many analysts believe that Athens will be forced to exit the eurozone shortly, dropping the euro currency and possibly further rattling economic confidence.
The fate of Greece was also front and center during a bilateral meeting Friday between Obama and newly elected French President Francois Hollande, who was elected on a platform opposing increasingly unpopular eurozone spending cuts.
Obama, who is hosting the Camp David summit, said he and Hollande agreed the issue was of "extraordinary importance" to the world economy.
"Greece must stay in the eurozone," Hollande insisted during his meeting with Obama. We all "must do what we can to that effect."
The G8 summit began Friday with a roundtable dinner. Discussion focused on security challenges in Iran, Syria, North Korea and Burma, according to the official, who spoke on condition of anonymity.
There was wide agreement among the leaders that North Korea faces further isolation if it continues its pursuit of a nuclear program, and they widely agreed that its Iran's responsibility to prove its nuclear program is being developed for peaceful purposes rather than the development of weapons, said the official, who spoke on condition of anonymity as a matter of practice.
The G8 leaders, who have been divided over how to respond to the conflict in Syria, agreed that a peace plan brokered by U.N. special envoy Kofi Annan was not being honored, the official said. Russian and China vetoed a U.N. Security Council condemning the violence and calling on President Bashar al-Assad to step down.
The leaders, including Russian Prime Minister Dmitry Medvedev, agreed it was time to focus on Syrian President Bashar al-Assad.
Russian President Vladimir Putin is not attending he G8 meeting, which makes significant progress on either Syria or Iran unlikely. Russia has been at odds with the United States and other G8 countries over exactly how hard to crack down on Damascus and Tehran.
On Sunday, the war in Afghanistan is expected to dominate discussions at the NATO summit. Afghan President Hamid Karzai and Pakistani President Asif Zardari are both expected to attend the meeting.
NATO leaders are currently on a timetable to withdraw all of the alliance's combat troops from Afghanistan in 2014.
Senior administration officials tell CNN that NATO members have tentatively agreed on a security transition plan from NATO's International Security Assistance Force to the Afghan National Security Forces before 2014. The plan, which also lays out a NATO training and advisory role after 2014, is expected to be formally adopted at the summit.
One of the key issues to be discussed in Chicago is who will pay to build up Afghan security forces during and after the NATO drawdown. Afghan national security forces should total around 350,000 by 2015, according to CNN National Security Analyst Peter Bergen. Karzai's government can afford to cover only a fraction of the cost, which is expected to total roughly $4 billion annually after 2014, Bergen notes.
Non-U.S. ISAF countries are being asked to come up with $1.3 billion, the officials said.
Another issue is Islamabad's continued blockade of much-needed NATO supplies over Pakistani roads to Afghanistan. Pakistan has kept its airspace open but closed its ground routes after the death of about two dozen Pakistani soldiers in November at the hands of NATO forces at a post on the Afghan-Pakistan border. NATO insists that the incident was an accident. Negotiations on the issue continue, the senior administration officials said.
Obama officials are also pushing for more Pakistani involvement in peace talks with the Taliban.
The United States also expects Hollande to announce the removal of French combat troops from Afghanistan -- a position he asserted during the presidential campaign.
Protests are expected near the sites of both the G8 and NATO summits this weekend.
"We expect the worst and hope for the best," said Ross Rice, an official with the Chicago FBI. That "is the way to characterize how the weekend plays out."