White House spokeswoman Sarah Sanders appeared to step back from US President Donald Trump's tweet earlier on Wednesday that missile strikes "will be coming" on Syria, saying no timetable has been set for US action, and no final decision has been made about whether an attack will even take place.
Asked about Mr Trump's warning to Russia on Wednesday that "nice, new and 'smart'" missiles will be targeting Syria, Ms Sanders said "that is certainly one option but it is not the only option or the only thing that the president may or may not do."
She continued to say that Mr Trump "has not laid out a timetable and is still leaving a number of other options on the table, and we're still considering a number of those." The president holds both the Syrian regime and Russia responsible for the chemical weapons attack, she added.
Ms Sanders stressed that “no final decision” has been made, and “all options remain on the table.” The White House spokeswoman expected the Syria debate to continue, with Mr Trump and his Defense Secretary James Mattis having both cancelled travel plans to focus on the issue at hand.
The Daily Beast reported on Wednesday that the head of the US Central Command General Joseph Votel has also cancelled a speaking engagement in New York planned for Thursday.
The delay in Mr Trump’s decision could be due to consultations both militarily and diplomatically with allies, especially France and the United Kingdom, in order to co-ordinate possible joint action, movement of military assets and targeting plans in Syria.
Carl Bildt, co-chair of the European Council on Foreign Relations and a former Swedish prime minister, saw the apparent de-escalation as a sign that the White House was thinking more strategically about its aims in attacking Syria.
Mr Mattis and the national security team had met on Wednesday at the White House, and Vice President Mike Pence chaired the meeting, Ms Sanders said.
Earlier, Mr Mattis presented the White House with a set of military options ahead of a possible strike in Syria in response to a chemical attack.
He told reporters at the Pentagon that these options are available, even as the US and allies are still in the process of gathering information.
"We are still assessing the intelligence, ourselves and our allies, we are still working on this," Mr Mattis said when asked if he had seen enough evidence to blame Syria President Bashar Al Assad for a chemical attack in Eastern Ghouta that killed at least 60 people and injured hundreds.
“We are ready to provide military options if they are appropriate” he added.
Shortly after the announcement, Mr Mattis discussed options with Mr Trump at a White House meeting.
Both the New York Times and The Wall Street Journal, quoting US officials, said an extended air campaign lasting more than one day is possible. "Options included salvos aimed at crippling Mr Assad's chemical-weapons capabilities, while not seeking to push him from power," a WSJ report said.
France President Emmanuel Macron on Wednesday was also briefed by Mr Mattis on the military options, French daily Le Figaro reported.
On the ground, the US navy reportedly moved warships carrying cruise missiles in the direction of the Mediterranean, towards a firing distance from Syria, the report said, adding that French Rafale fighter jets at Saint Robinson Dizier air base have been put on alert.
The Pentagon, however, refrained from confirming any military movement saying it did not comment on “potential military actions.”
Mr Trump had suggested what US military action might look like in his tweet on Wednesday.
The tweet was in response to Russian warnings that US intervention in Syria would be met with "grave repercussions."
"Get ready Russia, because they will be coming, nice and new and 'smart!'," Mr Trump tweeted in reference to US missiles.
But US strikes will only be effective so long as they can debilitate Mr Al Assad's war machine, said Nicholas Heras, a defence fellow at the Center for a New American Security.
"That means the United States and its allies will need to hit a range of targets that are both military and which are non-military targets that are significant to the regime" Mr Heras told The National.
“These targets could include forward operating bases, military airbases, intelligence buildings, and possibly the Assad family business assets.”
Meanwhile, the UAE expressed concern over developments in Syria and the UN's failure to take action.
"The United Arab Emirates calls upon the international community to take all the necessary measures to ensure the protection and safety of civilians, and ensure the cessation of violence that unfolded in the Syrian crisis," said the Ministry of Foreign Affairs and International Cooperation. "The UAE also calls for the establishment of a commission of inquiry and accountability on this heinous act."
At least 60 people were killed and hundreds injured in Saturday's chemical weapons attack in the town of Douma, in Eastern Ghouta, Syrian relief workers said. An estimated 500 people were being treated for "symptoms consistent with exposure to toxic chemicals," the World Health Organisation said on Wednesday.
The Syrian government and Russia, however, say the reports are bogus.
Moscow on Wednesday suggested US plans to strike Syria could be a pretext to destroy evidence of an alleged chemical weapons attack, which Russia has said was a staged "provocation" to justify Western intervention.
The escalation followed Russia's rejection of a US draft resolution at the UN that sought to create a new expert group that would determine responsibility for the attacks.
Syria's army reportedly has evacuated key defence buildings in Damascus following intelligence they might be targeted.