ISTANBUL — Turkey’s president announced Saturday that the country had launched a military operation in Syria’s northwestern Idlib province led by Turkish-backed Syrian opposition forces, to monitor the de-escalation effort and quell the Al Qaeda insurgency there.
The operation had been expected in the province, where Al Qaeda-linked fighters have wide influence.
A de-escalation zone was set up in the province after talks last month in the Kazakh capital of Astana during which Turkey, Iran, and Russia aimed at easing the fighting in the Syrian civil war.
The Turkish operation is aimed in part at crushing Al Qaeda in Idlib, in what may turn into a long and costly war. The extremist group has thousands of battle-hardened fighters and enjoys some popular support in the province, unlike the Islamic State.
Turkey is a strong backer of Syrian opposition fighters, while Iran and Russia back President Bashar Assad. Moscow joined the war two years ago siding with Assad, and Tehran has sent thousands of Iranian-backed fighters, tipping the balance of power in the president’s favor.
In late September, Russian President Vladimir Putin visited Turkey where he discussed the situation in Syria with Turkish President Recep Tayyip Erdogan. Last week, the Turkish leader went to Tehran.
Erdogan said the operation was a ‘‘new step’’ to establish security in Idlib, promising Turkey would not desert civilians there.
‘‘Today, there is a serious operation in Idlib and it will continue,’’ he said at his political party’s conference in Afyonkarahisar province in western Turkey.
Responding to journalists’ questions after the televised speech, Erdogan said: ‘‘The Free Syrian Army is leading an operation in Idlib right now,’’ referring to moderate rebel groups in Syria. He added that the Turkish military was not yet in the province.
The Britain-based Syrian Observatory for Human Rights, which has activists throughout Syria, said Turkish troops removed some walls in some areas along the border in order to allow vehicles to pass. It said Idlib is tense amid fear of clashes between Al Qaeda fighters and those of other militant groups.
The Observatory added that the expected Turkish operation in Idlib will be conducted under the cover of Russian airstrikes.
Turkey-backed Syrian forces are fighting the Al Qaeda-linked Levant Liberation Committee, formerly known as Nusra Front. In the past weeks, the Turkish military has been dispatching tanks and armored vehicles to the border with Idlib.
Turkish Chief of Staff General Hulusi Akar and Ground Forces Commander General Yasar Guler and Air Force Commander General Hasan Kucukakyuz arrived in the southern province of Hatay bordering Idlib Saturday to inspect preparations, according to a military statement.
A Syrian rebel commander speaking from Turkey said no military operations are ongoing at the moment but said preparations were underway for Turkish troops and FSA fighters to enter Idlib.
‘‘The aim of the operation is to implement the Astana agreement by setting up Turkish observation posts similar to those of Russia,’’ Lieutenant Colonel Fares al-Bayoush said.
‘‘This cannot be achieved without confronting the Nusra Front,’’ he said. ‘‘The aim is to finish Nusra Front.’’
Erdogan told journalists that Turkey would provide security inside Idlib, with Russia on the periphery. Iran, Turkey, and Russia reached the deal for four de-escalation zones earlier this year as part of their efforts to negotiate an end to the Syrian civil war.
Turkey’s official Anadolu news agency reported that the Turkish ‘‘deployment’’ would be to reach de-escalation goals rather than engage in clashes with local militia or the Syrian army.
The Turkish president warned his country would not permit a ‘‘terror corridor’’ along its border, referring to extremists groups as well as US-backed Syrian Kurdish militants.
‘‘The Idlib operation will allow us new initiatives on this issue,’’ Erdogan said, referring to Turkey’s aversion to Syrian Kurdish People’s Protection Units or YPG efforts to link up their semi-autonomous territories in northern Syria.
Last year, the Turkish army launched a cross-border operation with FSA to clear an area along its border of the Islamic State and prevent the YPG from gaining a foothold on the western banks of the Euphrates River.