If my memory serves me correctly, Magnier is a Kuwaiti analyst of Middle East military and political events. He has also earned the respect of one of America's foremost independent political bloggers at Moon of Alabama (Bernhard) who wrote on one of his posts referring to Magnier: "As he is one of the most knowledgeable experts on the war in Syria and Iraq his thoughts deserve a wider discussion."
Three Green Berets killed by ISIS infiltrator after CIA ignored warnings" (sourced from a website operated by veterans of Special Operations) offers more evidence that the US is training, funding, organizing, and weaponizing terrorist armies in Syria. (That is, if you had any doubts!)
The numerous terrorist armies have been assigned various names--probably to add more confusion to foreigners trying to figure out what is happening in Syria (also their attempt to separate terrorist armies from rebel armies)--have been recruited among Sunnis that had supported President Sadam Hussein and experienced torture at Abu Ghraib operated by the US military in Iraq, from the jails of Saudi Arabia, and dissidents from a variety of other Muslim countries in the Middle East. They have been trained and issued weapons by Saudi Arabia (and other affiliated Gulf feudal kingdoms, the US, and Turkey; and launched from Turkey, western Iraq, and Jordan to destabilize Syria. They have also been supported militarily and medically by Israel. Each of these players continue to have their own reasons for regime change in Syria.
Notice on this map that Sweida is, as Magnier wrote, near the Jordanian border, and Abu Kamal is in eastern Syria which lends support to his argument:
The United States has provided the necessary weapons for these rebel forces – the intensity of the usage of the anti-tank and anti-personnel TOWs laser guided missile is the best indicator. If these forces reach alBu [sic] Kamal (about 700 km from Suwayda), they would stop any possible intervention of Iraqi forces in Syria, under the pretext of hunting down ISIS to prevent their return to Iraq. In fact, this plan is not innocently aiming to disrupt the ISIS connection between Syria and Iraq, but to put an end to the “Shiite crescent”.
This “Shiite crescent” that the Sunni Gulf countries fear – not feared by the United States because it doesn’t represent any threat to the US security – is connecting Tehran, Baghdad, Damascus and Beirut.