Why would Saudi Arabia and Turkey send troops into Syria?

Saudi Arabia has announced its willingness to commit ground forces to the conflict in Syria, while Russia has accused Turkey of massing troops on the border in preparation for its own incursion into the war-torn country.

As the Syrian city of Aleppo appears on the verge of falling to government forces, backed by Russian air-power, why would the Saudis and their allies risk escalation by opening a ground front?

"Today, the Saudi kingdom announced its readiness to participate with ground troops with the US-led coalition against ISIL, because we now have the experience in Yemen," Brigadier General Ahmed Asseri of Saudi Arabia told Al Jazeera Thursday.

"We know that air strikes cannot be enough and that a ground operation is needed. We need to combine both to achieve better results on the ground."

Until now, the Saudis have limited their involvement to arming and supplying certain rebel groups in Syria. Sending their own troops into the fray would mark a significant turning point.

Major General Mohammad Ali Jafari, commander of Iran’s Islamic Revolution Guards Corps (IRGC), remains skeptical, reports Iran's Fars News Agency:

"They claim they will send troops [to Syria] but I don’t think they will dare do so. They have a classic army and history tells us such armies stand no chance in fighting irregular resistance forces," said Jafari.

The US reaction was more welcoming, with Defense Secretary Ashton Carter talking of a “desire to accelerate the campaign to defeat ISIL,” adding this would be much more successful “if other countries that are part of the coalition accelerate their efforts at the same time.”

Any Saudi Arabian intervention will likely operate in tandem with Turkish efforts, as the two countries set up a military coordination body a few weeks ago after expressing doubts that the Syrian debacle will ever be resolved politically.

Neither Saudi Arabia nor Turkey makes a secret of their desire to remove Syrian President Bashar al-Assad from power, leading some to doubt that an introduction of ground troops would be limited to the fight against the so-called Islamic State (known variously as Daesh, ISIL, ISIS, and IS).

“Although Riyadh states about the intention to fight against the Islamic State terrorist organization, there are big doubts about that,” said Vladimir Akhmetov, senior researcher at the Institute of Oriental Studies at the Russian Academy of Sciences, reported the Russian Tass News Agency.

“It is more likely that the Saudis intend to provide support to those armed formations which are fighting against the Syrian government forces.”

Yet the Saudis and Turks may be more interested in defeating IS than taking on the Syrian regime, at least overtly. Sending in ground forces to openly attack Syrian forces would be considered an act of aggression, and without international authorization, such a move could engender serious consequences, notes Abdulrahman al-Rashed of Al Arabiya.

Turkey has long had a military presence inside both Iraq and Syria, fighting IS while avoiding open confrontation with Assad’s forces, in spite of any desire to be rid of the Syrian regime, and in the face of hundreds of thousands of refugees flooding over its border.

The situation for Saudi Arabia is, perhaps, more straightforward:

“Saudi Arabia is not a neighboring country to Syria, as Iraq and Jordan separate both the countries,” writes Mr. al-Rashed. “It is also clear why Saudi Arabia is interested in fighting against ISIS in Syria. Like many other countries, it is aware that the organization will try and target the country at some stage.

“It is believed that hundreds of brainwashed Saudis are fighting there and some have even tried to return and carry out terrorist attacks inside Saudi Arabia. The rationale on which ISIS would like to target Saudi Arabia are explicit and similar to those of al-Qaeda.”

In addition, should IS be wiped out, it would be much harder for Russia and Iran to continue their military action, whether direct or by proxies, against other Syrian rebel groups, many of which are backed by Saudi Arabia and its allies.

Any escalation of the chaotic conflict in Syria could spiral into deeper mayhem, with the possibility of Saudi troops coming up against Iranian-backed Hezbollah forces, for example.

On the other hand, the entrance of foreign ground troops could reinvigorate diplomatic efforts to find a political resolution.