MUSCAT/BEIRUT: The Assad regime and its Russian allies are either incompetent or acting illegally by killing civilians in Eastern Ghouta, the US Defense Secretary Jim Mattis said on Sunday. Mattis also issued a new warning about the regime’s use of chemical weapons. “Right now we’re getting reports — I don’t have evidence that I can show you — but I’m aware of the reports of chlorine gas use,” he said before arriving in Oman on a trip to the Middle East. “There’s an awful lot of reports about chlorine gas use or about symptoms that could be resulting from chlorine gas.” Asked whether the US would respond militarily, as it did last year with missile strikes on a Syrian air base, Mattis said: “I’m not going to strictly define it, but we have made it very clear that it would be very unwise to use gas.” Mattis said the bloodbath in Eastern Ghouta, the opposition enclave near Damascus where the civilian death toll in the 22-day regime offensive rose on Sunday to at least 1,111, showed that regime troops were “at best indiscriminately” attacking and “at worst targeting hospitals.” “I don’t know which it is, whether they’re incompetent or whether they’re committing illegal acts or both,” he said. Russia could be complicit, Mattis said. “Either Russia is incompetent or in cahoots with Assad.” US President Trump Donald has said he will not tolerate chemical weapons attacks but has not yet made a decision about the latest reports, CIA Director Mike Pompeo said in Washington. “In this case, the intelligence community is working diligently to verify what happened there. “I’ve seen the pictures. You’ve seen the pictures as well. We have a higher standard to make sure we understand precisely what took place, precisely who did it, so that our response can meet the threat. “The president asks me nearly every day what it is the intelligence community knows about the Syrian regime’s use of chemical weapons and who else — the Russians or the Iranians — who might be responsible for them.” Assad regime forces have carved Eastern Ghouta into two, dealing a major setback to the opposition and threatening to exacerbate an already dire humanitarian situation. A military media outlet linked to the Syrian regime and its ally Hezbollah said pro-regime forces had broken through opposition lines to establish a corridor through the besieged region. In three weeks of fighting, regime forces have overrun more than half the area and split the remainder into three pockets, isolating the urban hub of Douma. On Sunday, regime troops battered the edges of each pocket with air raids, barrel bombs and rockets.