(CNN) -- US officials are crediting Russia with helping calm the situation in southern Syria, where the US has had to launch several airstrikes against Iranian backed Shia militias and pro-regime fighters in recent days.
Pentagon spokesman US Navy Captain Jeff Davis stated: "Russia has been very helpful and I think the calm that we see today is largely due to their efforts."
The incidents marked an escalation in the area around Al-Tanf, a garrison on the Syrian-Jordanian border manned by US and British Special Forces that are advising an anti-ISIS Syrian rebel group known as Maghawir al-Thawra, or the Commandos of the Revolution.
But the Pentagon is also stressing that it wants to remain focused on defeating ISIS and doesn't want to be diverted from its primary mission. "We are in Syria to defeat ISIS full-stop, anything else we do there is in self-defense only. We do not seek conflict with the Syrian regime or with these pro-regime militias or Iranian proxy forces," Davis said.
The US has been using its so called de-confliction communications line with Russia to request they call militias on the ground and get them to move to less threatening positions. A 55 kilometer de-confliction zone has been established around the garrison. While the zone has no formal legal standing, the US has dropped leaflets and passed messages via the Russians. Davis said there had been multiple contacts with Russia, including at senior military levels.
For their part, the Russians have been privately supportive of the US efforts, according to the Pentagon, although they have remained publicly critical. Russian Foreign Minister Sergei Lavrov, responding to a US airstrike in the area earlier in the week said, "The attack by the US led coalition in Al-Tanf region is an aggressive act infringing the sovereignty and the territorial integrity of the Syrian Arab Republic."
Privately, US military officials say they are hopeful matters will remain calm and no more US military action will be required. It reached a peak Thursday when a US F-15E jet shot down an Iranian-made Shahed 129 drone, which was being controlled from a location in Syria north of Al-Tanf, according to a US official. There were two additional US airstrikes this week against militia positions and vehicles, plus another airstrike in May.
Separately another US defense official said some 200 fighters remain several dozen miles outside of the de-confliction zone border with tanks and artillery. Currently they do not pose a threat, but the US is watching them carefully in case they move closer.
Until now, the US had viewed the Russians as having little influence over the militia units in the area.
"These are not forces that are under Russian command and control, these are pro-regime militias," Davis said, adding: "Russia is powerless to stop it but Russia can certainly pass these messages and relay our concerns and that seems to be working effectively."
Another US official told CNN they believe the militias were conducting probing attacks, setting up a series of check-points as part of an effort to establish a strategic overland route from Iran to the Mediterranean coast.
CNN's Tim Lister contributed reporting from Moscow.