Information Minister Omran al-Zoubi was quoted by the official state news agency, Syrian Arab News Agency (SANA), as saying that the government did not and would not use such weapons, if in fact they even existed. Al-Zoubi said, "everything that has been said is absurd, primitive, illogical and fabricated. What we say is what we mean: there is no use of such things (chemical weapons) at all, at least not by the Syrian army or the Syrian state, and it's easy to prove and it is not that complicated." SANA called the reports of chemical attacks as "untrue and designed to derail the ongoing UN inquiry." A Syrian military official appeared on state television denouncing the reports as "a desperate opposition attempt to make up for rebel defeats on the ground." Deputy Foreign Minister Faisal Mekdad declared it a tactic by the rebels to turn around the civil war which he said "they were losing" and that, though the government had admitted to having stocks of chemical weapons, stated they would never be used "inside Syria". Democratic Union Party leader Salih Muslim said he doubted that the Syrian government carried out the chemical attack.The National Coalition called the attack a "coup de grace that kills all hopes for a political solution in Syria." In a statement on Facebook, the Coventry-based Syrian Observatory for Human Rights, an anti-government activist network, blamed the attack on the Syrian military and said of the incident that "we assure the world that silence and inaction in the face of such gross and large-scale war crimes, committed in this instance by the Syrian regime, will only embolden the criminals to continue in this path. The international community is thus complicit in these crimes because of its [polarisation], silence and inability to work on a settlement that would lead to the end of the daily bloodshed in Syria."
Human Rights Watch stated that the UN Security Council should refer the Syria situation to the International Criminal Court (ICC) "to ensure accountability for all war crimes and crimes against humanity." Amnesty International also said that the Syria situation should be referred to the ICC because "the best way for the United States to signal its abhorrence for war crimes and crimes against humanity and to promote justice in Syria, would be to reaffirm its support for the Rome Statute establishing the International Criminal Court." However, as the amendment to the Rome Statute of the International Criminal Court explicitly making it a war crime to use chemical weapons in an internal conflict has not been ratified by any major state nor Syria, the legal situation is complex and reliant on the attack being a part of a wider war crime.
At the time of the attack, Syria was not a member of the Chemical Weapons Convention. However, Human Rights Watch argues that the Ghouta chemical attack was illegal under a different international agreement:Syria is a party to the 1925 Geneva Gas protocol, which bans the use in war of asphyxiating, poisonous or other gases, and of all analogous liquids, materials or devices. The use of chemical weapons is also prohibited as a matter of customary international humanitarian law, or the laws of war. The prohibition on the use of chemical weapons applies to all armed conflicts, including so-called non-international armed conflicts such as the current fighting in Syria. The International Criminal Tribunal for the former Yugoslavia, in the Tadic case, stated "there undisputedly emerged a general consensus in the international community on the principle that the use of [chemical] weapons is also prohibited in internal armed conflicts."
A report on the attacks by the United Kingdom's Joint Intelligence Committee (JIC) was published on 29 August 2013 prior to a vote on intervention by the House of Commons of the United Kingdom. The report said at least 350 people were killed and that it was "highly likely" that the attacks had been carried out by the Syrian government, resting in part on the firm view that the Syrian opposition was not capable of carrying out a chemical weapons attack on this scale, and on the JIC view that the Syrian government had used chemical weapons in the Syrian civil war on a small scale on 14 previous occasions. Analysis of the Ghouta attacks themselves was based largely on reviewing video footage and publicly available witness evidence. The report conceded problems with motivation for the attacks, saying there was "no obvious political or military trigger for regime use of CW on an apparently larger scale now." British officials said they believe the Syrian military used chemical weapons, including the nerve agent sarin, on a small scale against the opposition on at least 14 times prior to the Ghouta attacks and described "a clear pattern of regime use" of the nerve agent since 2012.The report was met with substantial scepticism in the British media, with the Daily Mail explicitly comparing it with the "dodgy dossier" the UK government had published in 2003 prior to the Iraq War. A vote in the House of Commons to approve UK participation in military action against Syria was narrowly rejected, with some MPs arguing that the case for Syrian government culpability was not sufficiently strong to justify approving action. Prime Minister David Cameron himself had been forced to concede that "in the end there is no 100 percent certainty about who is responsible."
The Turkish government-run Anadolu Agency published an unconfirmed report on 30 August 2013, pointing to the Syrian 155th Missile Brigade and the 4th Armored Division as the perpetrators of the two attacks. It said the attack had involved 15 to 20 missiles with chemical warheads at around 02:45 on 21 August, targeting residential areas between Douma and Zamalka in Eastern Ghouta. It claimed that the 155th Missile Brigade had used 9K52 Luna-M missiles, M600 missiles, or both, fired from Kufeyte, while other rockets with a 15- to 70-kilometer range were fired by the 4th Armored Division from Mount Qasioun. The agency did not explain its source.
松本サリン事件後に「サリン事件は、オウムである」などと書かれた「松本サリン事件に関する一考察」という怪文書が出回り、さらにオウムを追っていたジャーナリストの江川紹子が何者かに毒ガス攻撃を受ける（江川紹子ホスゲン襲撃事件）など、オウムと毒ガスの関係性が噂され始めた。1994年11月には強制捜査接近の噂迫が教団内に流れ、サリンプラントの建設を中断するなどの騒ぎとなっていた。そして1995年（平成7年）1月1日、読売新聞が上九一色村のサティアン周辺でサリン残留物が検出されたことを報じ、オウムへのサリン疑惑が表面化、教団は「上九一色村の肥料会社が教団に向けて毒ガス攻撃をしているため残留物が発見された」と虚偽の発表をするとともに、隠蔽工作に追われることとなった。だが麻原は1995年1月17日の阪神淡路大震災で強制捜査が立ち消えになったものと考え、1995年2月28日、東京都内で公証人役場事務長逮捕監禁致死事件を起こす。この事件で教団信者松本剛の指紋が発見されたことにより、ようやく警視庁は公証人役場事務長逮捕監禁致死事件で全国教団施設の一斉捜査を決定したのであった。3月15日には霞ケ関駅で自動式噴霧器が発見されたこともあり、毒ガスによる抵抗を想定して、陸上自衛隊から戦闘用防護衣450着と化学防護衣50着を借用するとともに、3月19日には警視庁機動隊員300名と捜査一課捜査員20名が朝霞駐屯地に派遣され、防護服の装着訓練を受けていた。