WASHINGTON (CBSDC/AP) — The United Nations is calling on the United States and its allies to wait longer on a potential military strike against Syria.

U.N. Secretary-General Ban Ki-moon said Wednesday that a team of U.N. chemical weapons inspectors needs a total of four days to complete its investigation into an alleged chemical weapons attack in Damascus in which Syrian activists say 1,300 people were killed.

“It is essential to establish the facts. A U.N. investigation team is now on the ground to do just that. Just days after the attack, they have collected valuable samples and interviewed victims and witnesses. The team needs time to do its job,” Ban said, according to CBS News, adding that a report needs to be sent to the U.N. Security Council.

U.N. envoy to Syria Lakdhar Brahimi said in Geneva that the Aug. 21 attack may have killed more than 1,000 people.

“With what has happened on the 21st of August last week, it does seem that some kind of substance was used that killed a lot of people: hundreds, definitely more than a hundred, some people say 300, some people say 600, maybe 1,000, maybe more than 1,000 people,” Brahimi said.

Brahimi backed Ban’s assertion that any possible military strike should go through the Security Council first.

“What they (Obama administration) will decide I don’t know. But certainly international law is very clear – the Security Council has to be brought in,” Brahimi said, according to CBS News, adding that the Obama administration was “not known to be trigger-happy.”

Vice President Joe Biden says there is no doubt that Syrian President Bashar Assad’s government is responsible for the heinous use of chemical weapons.

Biden’s comments Tuesday make him the highest-ranking U.S. official to say the Syrian regime is the culprit in a large-scale chemical weapons.

Biden says the Syrian government is the only actor in the 2-year civil war that possesses and can deliver chemical weapons. He says Assad has blocked U.N. investigators from the site and has been bombing it for days.

The White House says President Barack Obama hasn’t settled on how to respond to the attack. The Pentagon says U.S. military forces are ready to strike Syria if Obama gives the order.

We are prepared. We have moved assets in place to be able to fulfill and comply with whatever option the president wishes to take,” Secretary of Defense Chuck Hagel said.

White House Press Secretary Jay Carney said Tuesday that the administration is not contemplating about a regime change in Syria.

“The options that we are considering are not about regime change,” Carney told reporters at the White House press briefing. “They are about responding to the clear violation of an international standard that prohibits the use of chemical weapons.”

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