ISTANBUL -- From the start of Syria's civil war, rebels fighting President Bashar al-Assad have had no better ally than Turkey's prime minister, Recep Tayyip Erdogan. He has effectively kept Turkey's border with Syria open, allowing fighters a haven in the south of his country as weapons, cash and other supplies have flowed to the battlefield.
He has even fired on Mr. Assad's forces.
But now, Turkey finds itself in the same position as many of the rebels' early backers, including the United States -- concerned that Islamist radicals have come to dominate the ranks of the Syrian opposition. It shelled rebel positions this week for the first time since the war started, in yet another positive turn for Mr. Assad, who has found his position increasingly stable, if not secure.
Mr. Erdogan was one of the first world leaders to call for Mr. Assad to step down, and from the start he provided a lifeline to the rebels. But with radical Islamists controlling territory along the Turkish border, and the United States working with the Assad government to rid it of chemical weapons, his policy is in turmoil and his country without a viable ally in Syria. Mr. Erdogan has himself been criticized for allowing weapons to get into the hands of jihadists.
The shelling of rebel positions this week "was a signal that they wanted to show everybody that they wanted to take a different line on this," said Henri J. Barkey, an expert on Turkey and a professor of international relations at Lehigh University. "It's just symbolic. It's a way of telling the rest of the world that we are taking a stand against these Al Qaeda-type guys."
While many countries -- including the United States, which recently contemplated military strikes against Syria in response to the use of chemical weapons there -- have called for Mr. Assad to go, the focus has lately shifted to seeking and carrying out a political solution, or what Washington has referred to as an orderly transition of power.
On Thursday, Secretary of State John Kerry reinforced that position when he said in an interview with NPR that a political solution would seek to "maintain the institutions of state." At the same time, a Syrian government official said that long-delayed peace talks might finally be held in Geneva next month.
The shift in international sentiment has been particularly challenging for Mr. Erdogan, who continues to support the rebels but is concerned about security along the border as a flurry of Turks have crossed into Syria to join the ranks of the jihadists. At the same time, Turkey is struggling with cascading crises that have undermined its regional role, forcing it to look more inward.
At the height of the Arab Spring, Mr. Erdogan offered Turkey as a model of democracy and Islam for Egypt and other nations that had cast off dictators. But he has had to confront widespread demonstrations at home criticizing his authoritarian style, and abroad he has seen allies in Egypt ousted by the military.
The strikes by the Turkish Army this week, in response to a shell that landed inside Turkey without causing damage, seemed aimed at countering criticism that Turkey had fostered the growth of jihadist groups.
But they also seemed to underscore Turkey's troubled Syria policy as it seeks to recalibrate its tactics, supporting yet targeting the rebels, all while calling for Mr. Assad to step down.
"They still feel that the only way to solve the crisis is to force Assad from power, and that the only way to do that is to funnel weapons to the opposition," said Aaron Stein, an associate fellow at the Royal United Services Institute for Defense and Security Studies who writes on security issues in Turkey. "They only have buyer's remorse because they depended on the Obama administration to come to the rescue."
By now, Turkey had expected that the United States and its Western allies would have increased military support for the rebels. While the United States has provided some training and arms, Mr. Obama called off the missile strikes he had threatened in response to a chemical attack in August. Turkey was angered when the tide shifted from imminent military action to diplomacy, Mr. Stein said, because the chemical weapons pact suggests that Mr. Assad "will be around a long time to implement the deal."
He added that Turkish leaders "felt they were hung out to dry" when the Obama administration shelved its plans for military action.
Turkey's Syria policy is also deeply unpopular among the Turkish public and has become a domestic political challenge for Mr. Erdogan, who has been in power for more than a decade and is considering a campaign for the presidency next year. Nearly from the beginning of the Syrian uprising, Turkey has sought to shape its outcome by pushing Mr. Assad to liberalize the political process. But when the rebellion turned violent, Turkey opened its borders to Syrian refugees, whose ranks within Turkey have swelled to more than 500,000, earning the country praise from the international community but raising ethnic tensions in the border region.
In contrast to countries like Jordan, which has kept its border tightly controlled, Turkey initially allowed the free flow of fighters and weapons to support the opposition, which was dominated at first by moderate groups but eventually overtaken by more experienced, and more extreme, jihadist fighting groups.
"They weren't necessarily arming Al Qaeda, but they just weren't policing their borders," Mr. Stein said.
Kadri Gursel, a political analyst here and a columnist for the newspaper Milliyet, said, "Turkey continues to deny any support for the Al Qaeda rebels, but the fact that so few precautions have been taken against them, and no obstacles have been put into place, is support in and of itself."
Referring to the strikes on Islamist militant positions in Syria, Mr. Gursel said, "With this latest move, Turkey is trying to rebuild the image of its Syria policy and show that no security threats will be tolerated from anyone."
More broadly, many analysts here see the failure of Turkey's policy to result in a peaceful outcome in Syria as a rebuke to the efforts by Mr. Erdogan's Islamist governing party -- the Justice and Development Party, known by its Turkish initials, A.K.P. -- to present Turkey as a pivotal player in shaping regional affairs. Particularly when seen alongside events in Egypt, where the military overthrew a Muslim Brotherhood-dominated government that had close ties to the A.K.P., many say the course the Syrian conflict has taken represents a severe blow to Turkey's regional aspirations.
"It seems that Turkey's influence in the region is not being viewed positively in the wake of the Syrian and Egyptian crises," Fuat Keyman, a columnist, wrote this week. "The Turkish model is not being discussed anymore. And in the context of the Arab Spring and ongoing developments in the Middle East, that means Turkey risks losing its place and role in regional politics."
Ceylan Yeginsu and Sebnem Arsu contributed reporting from Istanbul, and Alan Cowell from London.
This article originally appeared in The New York Times. First Published October 18, 2013 2:01 PM