CAMP DAVID, Maryland (AP) ― President Barack Obama and leaders of other major industrial powers grappled Friday with options to solidify world resolve against development of an Iranian nuclear bomb and encourage a more forceful response to worsening violence in Syria.

Obama will have the ear of key players on both issues during back-to-back G8 and NATO summits that will be dominated with discussions of European economic woes and Afghanistan. Talks about Syria and Iran will be aimed directly and indirectly at Russia, a sometime protector of both Iran and Syria and the chief blockade to such U.S. goals as an arms embargo on Syria.

The gatherings come in the shadow of the eurozone debt crisis and plummeting public support for the war in Afghanistan. Political and economic chaos in Greece and Spain underscored just how fragile Europe’s economy remains after an eviscerating austerity regime. Germany’s finance minister predicted Friday that the crisis could last up to another two years.

German Chanceller Angela Merkel will face a push from Obama and new French President Francois Hollande for more measures aimed at spurring economic growth. Merkel has pushed for countries to cut their budget deficits to stop piling up added debt. But steep cutbacks in government spending have stalled the economy in the 17 countries that use the euro.

Obama’s re-election campaign could be complicated by more economic deterioration in Europe, a key U.S. trade partner, or by financial chaos if heavily indebted Greece winds up leaving the euro currency.

Obama said managing the fiscal crisis in Europe must be coupled with a “strong growth agenda.’’ Hollande won election May 6 urging growth measures be added to a European treaty aimed at restricting spending.

Growth steps could include letting Spain and other countries slow its their efforts to cut deficits or more flexible use of unspent EU infrastructure funds.

Hollande said that it would be “useful’’ for Spain to recapitalize its shaky banks using “the mechanisms of European solidarity.’’ Europe’s bailout fund can lend governments money to bail out banks. Spain’s banks are believed to harbor large losses from a collapsed real estate boom, losses which could burden government finances if it comes to bailouts.

Most of the leaders are part of overlapping international coalitions formed to address the Iranian nuclear problem and the newer crisis in Syria, where an estimated 9,000 people have died in more than a year of violence that arose from the pro-democracy Arab uprisings.

Faced with implacable Russian opposition to significant new United Nations punishments on the Syrian regime of President Bashar Assad, U.S. officials are trying to get consensus among other allies about ways to promote Assad’s ouster.

A senior U.S. official said one goal of Friday’s closed-door discussion at the secluded presidential retreat in Camp David, Maryland, was to impress on Russian Prime Minister Dmitry Medvedev that other nations that share Russia’s usual role at the forefront of international diplomacy are seeking ways to address the Syria debacle without Russian help.

Obama greeted each leader by name, calling Medvedev “my friend,” before the group went inside for dinner.

The United States wants to avoid escalating a confrontation with Moscow over Syria, the official said, but wants Medvedev to hear the depth of international outrage. The official spoke on condition of anonymity to discuss internal diplomacy.

A senior Obama administration official said Friday night that the Group of Eight leaders unified behind a dual track effort of sanctions and diplomacy toward Iran and agreed to focus on political transition in Syria.

The eight leaders gathered for a dinner of more than two hours in the secluded woods of Camp David, the presidential retreat in Maryland’s Catoctin Mountains.

The official spoke on the condition of anonymity to share details of the private session.

Russia is a partner with the United States and European nations in containing Iran’s nuclear program, although with China it has blocked the most severe penalties the United Nations Security Council might impose. A U.N.-affiliated negotiating group including Russia will meet with Iranian officials next week in Baghdad, Iraq.

On Iran, the U.S. official said each of the leaders, including Medvedev, indicated that Iran has the burden of proving that its nuclear program is for peaceful purposes.

As for Syria, the official said the leaders continued to back the peace plan brokered by special envoy Kofi Annan brokered in April, including its call for political transition. But they did not go beyond that.

U.S. officials say the economic pressure of sanctions is key to drawing Iran back to the bargaining table this spring after a long hiatus.

“Each member of the G8 is a core member of this sanctions effort,” White House national security adviser Thomas Donilon said Thursday. “Each member has been absolutely essential to really putting in place what has been an extraordinarily effective and, I think most people would say, surprisingly effective sanctions effort.”

Iran says it is enriching only to create nuclear fuel. Its refusal to halt enrichment has provoked U.N. and other sanctions, including U.S. and European Union penalties meant to cripple its oil exports ― its main revenue source ― that are to fully take effect in a few weeks.

“The message will be that the Iranians should seize this opportunity” for talks, Donilon said. “And while this goes on, in parallel, the sanctions and pressure effort will continue, led by the United States and the others who will be at the table on Friday evening.”

Syria is a much harder case, in part because Russia and China oppose U.N. action that could set a precedent for outside interference in internal ethnic or human rights matters, and partly because there is no international appetite for a military confrontation with Assad.

Syrian forces on Friday fired on protesters holding the largest opposition marches yet in Aleppo, a sign of rising anti-regime sentiment in the country’s biggest city, which has largely remained supportive of President Bashar Assad throughout the 15-month uprising.

The head of the U.N. observer mission in Syria warned that neither his team nor armed action could solve the country’s crisis, and called on all sides to discuss a solution. But the regime kept up its assaults on opposition areas and protests, while the head of Syria’s largest exile opposition group dismissed the U.N.’s plan as unrealistic.

The White House abruptly moved the G8 session to Camp David earlier this spring, after months of planning for a Chicago venue. A desire for seclusion and intimacy was one reason and a gesture to Russia was another.

Russia is opposed to a NATO plan for a missile defense shield in Europe that will be detailed at the NATO summit Sunday in Chicago, causing Russian President Vladimir Putin to let NATO know he did not want to be invited to the alliance meeting.

Separating the two sessions was supposed to make it easier for Putin to attend one and not the other. But Putin made his own abrupt change, telling Obama last week that he would skip the gathering and send Medvedev in his place.

The administration denied speculation that the sessions were moved for security reasons. Past G8 meetings have seen large and sometimes violent protests by activists opposed to the increasing globalization of world economies. Street violence overshadowed the 2001 summit in Genoa, Italy. Critics have accused the G8 of representing the interests of an elite group of industrialized nations to the detriment of the needs of the wider world. Since Genoa, the meetings have been held in increasingly isolated locations to shield leaders from protests, playing into criticism of the G8’s closed-door image.

Obama, an infrequent visitor to Camp David, is putting the presidential hideaway on full display for the G8, the largest gathering of foreign leaders ever to assemble there. The leaders will stroll leafy paths to rustic meetings halls and bed down in the 11 residential cabins. Four African leaders will join them for lunch Saturday.

The G8 is made up of the leaders of the United States, Japan, Britain, Germany, France, Italy, Canada and Russia. The meetings began in 1975 at a forum instigated by France, where leaders of the six largest economic powers agreed to annual meetings. Canada joined a year later, making it the G-7. Russia was brought into the organization in 1997, six years after the collapse of the Soviet Union. The European Union is represented but is not granted the power to act as host of the annual sessions or to serve as the rotating leader.