WASHINGTON – The Trump administration is documenting atrocities committed by the regime of Bashar Assad in Syria, hoping to eventually build cases against their perpetrators for international criminal prosecution, US National Security Adviser H.R. McMaster said on Thursday.Speaking at the US Holocaust Memorial Museum in Washington on the seventh anniversary of the start of Syria’s civil war, McMaster said the US would continue declassifying information that would shed light on Assad’s war crimes. He pointed to the administration’s decision last spring to publicly reveal the existence of a crematorium at Sednaya Prison outside Damascus, which US intelligence agencies believe has been used to cover up evidence of mass killing.The US would actively support the United Nation’s independent commission on criminal inquiry on Syria, as well as its international, impartial and independent mechanism to assist in the investigation and prosecution of those responsible for the most serious crimes in Syria, the senior official said.And yet, while McMaster said the Trump administration recognizes that action is required to prevent further genocide in Syria, a report on the crisis released by the Holocaust Museum on Thursday offered the White House no such credit.“There is no indication that Assad perceives any consequences for, or a credible deterrent to, the ongoing commission of atrocities,” the report reads. “Thus far it appears that no government or international organization has been able or willing to stop him. In an environment that he regards as permissive, he will continue to target civilians with impunity until he has achieved and sustained his goal of holding onto power or is stopped.”Roughly 500,000 Syrians have been killed in the conflict, while five million have fled the country and over six million have been internally displaced by the fighting. The Holocaust Museum has warned that – with several cities filled with starving civilians under siege by the Assad government, aided by the governments of Russia and Iran – the worst may still be yet to come.“It is time to impose serious political and economic consequences on Moscow and Tehran,” McMaster said. He vowed that US President Donald Trump would respond to the continued deployment of chemical weapons by the Syrian government against civilians. Taking note of Russia’s use of a nerve agent in the streets of a British city earlier this month, McMaster warned that such events are all part of a concerning pattern of disregard of a historic international ban on their use.McMaster warned Iran was seeking to build a “permanent military foothold” in Syria that would “threaten Israel” and challenge US interests region wide. “We cannot let this happen,” he charged.He also accused the Islamic Republic of using civilian aircraft to transport military personnel and equipment from Iran to Syria – a violation of Tehran’s multi-billion dollar agreements with Boeing and Airbus, facilitated by terms codified in its 2015 nuclear deal with world powers.