On 23 August, U.S. and European security sources made a preliminary assessment that chemical weapons were used by Syrian forces, probably with high-level approval from the Assad government.
[78] Citing unidentified sources, Foreign Policy's online Cable channel reported that "U.S. intelligence services" intercepted communications between an official at the Syrian Ministry of Defense and the leader of a chemical-weapons unit, demanding an explanation for a nerve-agent strike hours after the attack.
[79][80] Russian President Vladimir Putin[81] told British Prime Minister David Cameron that there was no evidence that the chemical weapons were used by the Syrian government.
An Iranian Foreign Ministry official said that Russia submitted evidence to the UN Security Council (including satellite images)[citation needed] allegedly proving that chemical weapons were used by the opposition and not the government.
[84][85] The United States reportedly planned to launch up to 100 Tomahawk cruise missiles against the Syrian Army,[86] but after several days of public indecision about how to respond to the attacks, President Obama said on 31 August that he would seek congressional authorization before approving military action (although he thought punitive strikes were warranted).
[87] No vote in Congress was held, but the United States Senate Committee on Foreign Relations did approve the Authorization for the Use of Military Force Against the Government of Syria to Respond to Use of Chemical Weapons (S.J.Res 21) on 4 September, which would allow the president to take direct action for up to 90 days, but specifically forbid "boots on the ground".
[95] Swedish Defense Research Agency Middle East expert Magnus Norell said, "Taking things through the UN Security Council is just an excuse to not do something, because you know that a veto will be passed ...
[109][110] United Nations Secretary General Ban Ki-Moon said, "The use of force is lawful only when in exercise of self-defense, or when the Security Council approves such action".
[118] The USS Harry S. Truman carrier strike group including the Ticonderoga-class cruisers Gettysburg and San Jacinto and the Arleigh Burke-class destroyers Bulkeley and Mason transited the Suez Canal on 18 August on their way to the Indian Ocean,[119] where they relieved the USS Nimitz carrier strike group (which moved into the Red Sea on 1 September, placing it within easy deployment range of the eastern Mediterranean).
The other ships in the Nimitz carrier strike group were the Ticonderoga-class cruiser Princeton and the three Arleigh Burke-class destroyers Shoup, Stockdale and William P.
[126] On 30 August the amphibious transport dock USS San Antonio arrived in the eastern Mediterranean to join the five destroyers there, carrying elements of the 26th Marine Expeditionary Unit.
[130] On 4 September the Italian Navy Orizzonte-class frigate Andrea Doria and the Maestrale-class frigate Maestrale left their home port of Taranto for the eastern Mediterranean,[131] and the Italian Navy Durand de la Penne-class destroyer Francesco Mimbelli and the Sauro-class submarine Salvatore Pelosi were deployed to the Ionian Sea.
[133] After a U.S. suggestion that a handover of Syrian chemical weapons within a week might avert military action, Russia and Syria began to pursue this solution.
[137] In Foreign Policy, Yochi Dreazen wrote that implementing such a plan would not be easy: "Taking control of Assad's enormous stores of the munitions would be difficult to do in the midst of a brutal civil war.
[139] A pre-Geneva II preparation meeting planned by senior U.S. and Russian diplomats for 28 August 2013 in The Hague was postponed by the U.S. Department of State because of "ongoing consultations" about the attacks.
According to a State Department spokesperson, the U.S. "would work with Russia to reschedule [the] planned meeting and that the alleged chemical weapons attack demonstrated the need for a 'comprehensive and durable political solution'.