"This map provides a general look at the recent gains by Turkish-led forces in southern Idlib. The Turkish Army and its al-Qaeda-linked allies have retaken several villages from the Syrian army and beiseged the town of Kafr Nabul, which the Syrians had recently liberated from al-Qaeda." SF
IMO the gains made by the jihadis and the Turkish Army in Idlib Province are being made because of the masses of artillery weapons and multiple launcher rocket systems (MLRS) that the Turks were equipped with when they were a major factor in NATO plans to halt a possible Soviet attack in the Balkans and from the Caucasus.
A lot of these weapons are old but they still work well and have ranges that can influence the fighting in Syria from positions WITHIN Hatay Province, Turkey (what the Russians now call "the stolen province"). We are talking about 203 MM howitzers and 175 mm long rifles among other weapons. I can tell you from personal experience that these are devastating weapons.
The appropriate military response to fires from such artillery and MLRS is COUNTER-BATTERY FIRE. IOW the point of origin of the fires is determined virtually instantaneously by counter-battery radar or satellite observation (Russian) and fires are placed on the firing positions before the guns or MLRS can be moved. This procedure would kill a lot of Turks and destroy a lot of their equipment. IMO it would stop the present Turkish counter-offensive. Could Fatih Sultan Tayyip politically survive such an experience? Only Allah knows.
The NATO Treaty's Article Five provides for mutual defense against attacks from outside the alliance. Would counter-battery fire against the Turks, if they are firing into Syria, trigger Article Five? I doubt that the Europeans would want to go to war against Russia to protect the sultan's ambitions. Counter-battery fir against Turkish artillery operating INSIDE Syria would no be a political problem involving NATO.
The Turks must have moved some guns forward into Syria to support the Turco/jihadi force around Saraqib. Some other group of heavy weapons must be supporting the Turco/jihadi force near the northern el-Ghaab Plain. Are they in Syria? Maybe, but wherever they are, IMO they can be struck without fear of Article Five.
Would the Syrians then be attacked by US forces with or without Article Five? Maybe they would be. That would depend on the level of Pompeo's influence with the president. pl