ISTANBUL - Turkish forces set up a military post southwest of the Syrian city of Aleppo on Monday, the army said, the deepest position they have established so far inside northwest Syria under a deal with Russia and Iran aimed at reducing violence there.
The announcement came six days after a large Turkish military convoy, heading for the same area, came under attack and had to pull back.
Under the deal reached with Tehran and Moscow to try to reduce fighting between pro-government forces and mainly Islamist insurgents in the northwest Syria, Turkey agreed to set up 12 observation posts in Idlib and neighboring provinces.
But the "de-escalation" in violence they were supposed to monitor has collapsed. In December, the Syrian army alongside Iranian-backed militias and heavy Russian air power launched a major offensive to take territory in Idlib province.
The Syrian civil war, now entering its eighth year, has killed hundreds of thousands of people and driven more than 11 million from their homes.
Idlib is one of the last main strongholds of rebels opposed to President Bashar Assad, who have been driven from most of their bastions in Syria since Russia joined the war on the side of Assad's government in 2015. Turkey has long been one of the main allies of the anti-Assad rebels.
Separate from the so-called de-escalation operation agreed with Russia and Iran, Turkey launched an offensive two weeks ago into another neighboring part of Syria, the Afrin region, against Kurdish fighters who control it.
Russian jets intensified raids on Sunday against rebel-held towns in Idlib, after rebels shot down a Russian warplane and killed its pilot on Saturday.
The Syrian Observatory for Human Rights monitoring group said the new Turkish observation post was near the village of El-Ais.
That would place it less than five km (three miles) from territory held by Syrian government forces and their allies, and deeper inside Syria than the three observation posts set up by the Turkish army so far.
The military said in a statement on Monday there were plans to begin reconnaissance work on establishing two more observation posts.