Toretsk (Ukraine) (AFP) – First there was a teasing crackle of small arms fire then a burst of sharp bangs as Ukrainian assault infantry fired their US-made grenade launder at the Russian positions opposite. The frontline in this part of the Donetsk region in eastern Ukraine has been fairly stable since 2014, when Moscow’s proxy forces in the so-called Donetsk People’s Republic (DNR) seized an enclave. But many Western weapons — like the Mk-19 automatic grenade launcher — have only arrived on this battlefield since February this year, when Russia escalated the conflict with a full-scale inva…