Syria army begins offensive near Aleppo with Russian support

The offensive came as Turkey said it had downed a drone of unknown origin that violated its airspace close to the Syrian border, and a monitor said the death toll in the conflict had risen to more than 250,000.

Mr Putin's comments come a day after president Barack Obama announced plans to keep about 9,800 USA troops in place in Afghanistan through most of next year to continue counter-terrorism missions and advise Afghans who are battling a resurgent Taliban. Simply opposing Putin will get the USA nowhere.

The only thing President Obama and Russian President Vladimir Putin agree on in Syria is making sure their respective militaries don't run into each other, Obama said on Friday. It didn't specify how it had relayed the warnings to the operators of the drone.

Russian Federation said all its planes in Syria were safe and its drones "working as normal".

Russia, an ally of al-Assad, has denied reports about civilian casualties resulting from its air campaign that started in Syria on September 30.

"Of course we are not fighting for specific leaders, we are defending our national interests, on the one hand", Medvedev said in an interview to air on state television.

Meanwhile, Kazakhstan's military experts treat the operation in Syria that involves Russian forces quite skeptically.

The Lebanon-based pro-Syrian Al-Mayadeen TV quoted an unnamed Syrian military official as saying that no Syrian or Russian warplane or drone was shot down over Turkey.

The offensive that began before dawn builds on more than a week of ground attacks launched with Russian air support in areas of western Syria that are crucial to Assad's survival and held by rebel groups other than ISIS.

But the United States suspected that Turkish fighters targeted a Russian drone, the Reuters news agency reported, citing a USA official speaking on condition of anonymity.

A fighter from the Free Syrian Army's Al Rahman legion fires on the frontline against the forces of Syrian President Bashar Assad in Jobar, Syria, near Damascus, July 27, 2015. "We have arrived at an understanding and a few channels for communications".

That has left Syria's airspace crowded with warplanes from rival, or even hostile powers, pursuing competing military strategies, heightening the risk of aerial confrontation.

While vast numbers of Syrians have embarked on the risky voyage to seek safety in the European Union, those in the small community living in Russian Federation mostly have longstanding diplomatic or family ties to the country.

There has already been a third video conference with the US, concerning the drafting of the memorandum between the two defense ministries on the prevention of incidents and flight safety in the sky over Syria, the general said. "We expect this document to be signed very soon". It said it was not immediately clear which country the aircraft belonged to.

These air defenses, Kartapolov said, will not be used against the U.S.-led anti-IS coalition.

Kartapolov also accused the USA coalition of bombing infrastructure essential to a ground operation by the Syrian army.

Syrian troops backed by Russian air strikes are pressing ahead with an assault against rebels in central and northern Syria, to the Syrian government and opposition activists. The incident highlights the dangers of multiple countries launching air offensives over Syria in order to curtail the rampant insurgency within the country.