There is no better lesson about the perils of setting up a safe zone in a country in conflict than Srebrenica, where Bosnian Serbs killed some 8,000 Muslim men and boys in 1995 in what had been declared a U.N.-protected enclave. Now Turkey is pressing the United Nations to set up a safe haven inside Syria to protect thousands of people fleeing the country's civil war as it strains to shelter an increasing flow of refugees.

Mindful of that bloody episode in the Balkans — Europe's worst massacre since World War II — Turkey and its allies, particularly the United States, have conducted detailed planning and extensive diplomacy ahead of a possible occupation of some territory in Syria, where activists say more than 20,000 people have died since an uprising began in March 2011 — many of them civilians killed by regime forces.

Yet the idea of a buffer zone, or no-fly zone — or more likely a combination of the two — still poses complex legal and logistical challenges, as well as fears that intervention could trigger reprisal attacks and end up widening the conflict in an already combustible region.

Turkey's Foreign Minister Ahmet Davutoglu said Wednesday that he would press the U.N. Security Council on Thursday at a high-level meeting in New York to set up the safe zone, reflecting frustration at the failure of rhetoric, diplomacy, economic pressure and aid for the Syrian opposition to stop the bloodshed. However, such action amounts to military intervention because a security force would have to guard civilians, and Russia, an ally of Syria that has a military base there, and China have used their council votes to block action against Syrian President Bashar Assad.

"We expect the U.N. to step in and protect the refugees inside Syria, and if possible, to shelter them in camps there," Davutoglu said. "When refugee numbers reach hundreds of thousands, this problem goes beyond being an internal issue and becomes an international one. No one has the right to expect Turkey to take on this international responsibility on its own."

Turkey has long floated the idea of a buffer zone to protect displaced Syrians from attacks by Syrian regime forces, but the issue is more pressing because the number of refugees in Turkey has exceeded 80,000 — an amount it says approaches its limits. The U.N. refugee agency has said up to 200,000 refugees could eventually flee to Turkey, which shares a 566-mile (911-kilometer) frontier with Syria. Tens of thousands of Syrians have also fled to Lebanon, Iraq and Jordan.

However, the humanitarian crisis is clouded by geopolitical interests and rivalries. Russia felt betrayed by the NATO military mission in Libya, where it believes a U.N. mandate to protect civilians from attacks by forces loyal to dictator Moammar Gadhafi was used as legal cover to unseat him.

If Russian cannot be persuaded, a group of allies, including the U.S., Turkey, France, Qatar and Saudi Arabia, could choose to proceed with a safe zone without the legitimacy of a U.N. resolution. But Assad, who still counts regional power Iran among his few supporters, could gain political capital by characterizing an intervention as a Western or sectarian vendetta against him.

With Syria known to be in possession of chemical weapons, and Israel pondering an attack on Iran's nuclear facilities, allied planners must consider the worst-case scenarios of intervention — an especially unappetizing prospect for the U.S. administration ahead of a presidential election in November. Turkey has said it will not act alone.

"Legally they need U.N. approval to create a buffer zone or no-fly-zone, but it doesn't seem possible in the near future because of Russia's opposition in the Security Council," said Ercument Tezcan, an international law expert at USAK, a research center based in Ankara, the Turkish capital. Still, he said, allies could establish a no-fly zone in Syria, just as U.S.-led powers did in Iraq after the 1991 Gulf War to protect Kurds and Shiite Muslims from dictator Saddam Hussein, and enforce it on the basis of humanitarian intervention even though they would be violating Syria's sovereignty.

"There is no legal definition of humanitarian intervention," Tezcan said. "It just needs strong willpower, but these countries may be criticized by their publics and by history."

Foreign Minister Laurent Fabius of France, which backs Turkey's idea for buffer zones, said in an interview Wednesday on France-Inter radio that setting them up without an internationally imposed no-fly zone to protect civilians is impossible.

"We continue to believe despite all the limits that there are, that something can be done in international legality," he said, citing Russo-Chinese vetoes on tougher U.N. language against Syria. "We cannot just sit idly by."

Since the powers that would establish any safe zone are also calling for Assad's ouster and supporting the Syrian opposition, a so-called humanitarian mission could easily be construed as the first step in regime change managed from the outside. There would be concerns about whether Syrian rebels are using any foreign-protected camps to stage attacks on regime forces, which in turn could try to launch long-range artillery or air strikes on those same locations inside Syria.

The grave burden of protecting civilians was evident at Srebrenica, where thousands were slain in summary executions and their bodies plowed into mass graves. International courts have ruled the massacre amounted to genocide. Dutch troops stationed in the enclave as U.N. peacekeepers were undermanned and outgunned, and failed to intervene.

"To be effective, a safe zone requires a serious armed force that can defend it and serious logistics to supply it and that means a lot of military boots on the ground and serious commitment," said Emir Suljagic, a survivor of the Srebrenica massacre who had worked as an interpreter for U.N. forces based in the town. He advocated an allied bombing campaign in Syria along the lines of those in Libya and Kosovo on the basis that, "the only answer to such violence is equally extensive violence."

Bosnian Serbs also took peacekeeping soldiers hostage in an attempt to deter United Nations commanders from ordering NATO air strikes against Serb forces surrounding Bosnian safe zones. This hostage situation blocked any serious military action by the U.N.

In 1994, under a U.N. mandate, France established a humanitarian zone in Rwanda in response to the genocide there, but the project was plagued by accusations that perpetrators of the violence benefited from it.

Human Rights Watch has urged countries that have taken in Syrian refugees to keep their borders open despite the pressure of greater numbers, and said the international community should contribute aid. In Beirut, HRW representative Lama Fakih expressed concern that the establishment of any safe zone could leave fleeing civilians in a potentially more precarious situation against their will.

"Under international law, they have a right to be able to leave their country and seek asylum in another country," Fakih said.

Turkey has experience with a buffer zone, helping to set one up in 1991 to deal with hundreds of thousands of Kurdish refugees flooding to the border from Iraq during Saddam's war with a U.S.-led coalition. International aid groups assisted Kurds on the Iraqi side of the border. The numbers flooding across from Syria are not as great, but Turkey is building four new camps to accommodate new arrivals. One opened late Tuesday, allowing authorities to start letting in several thousand more displaced Syrians who were waiting on the Syrian side of the border.

"If the situation in Syria becomes graver, it is possible that we will experience a mass exodus," said Atilla Sandikli, an analyst at BILGESAM, a research center in Istanbul. "A buffer zone has become inevitable."


Associated Press writers Suzan Fraser in Ankara, Turkey; Aida Cerkez in Sarajevo, Bosnia-Herzegovina; and Jamey Keaten in Paris contributed.