BANDER SERI BEGAWAN, Brunei -- With its military ready to attack Syria on President Obama’s command, the United States is no longer pursuing a United Nations or NATO stamp of approval to respond with force to the purported deployment of chemical weapons.

Instead, the U.S. has focused on building a rapid coalition consisting of the United Kingdom, France and several Arab states, by sharing intelligence evidence that U.S. officials say proves Bashir al Assad’s regime was responsible for last week’s chemical weapons attack.

“Syria used chemical weapons against its own people,” Defense Secretary Chuck Hagel said in a BBC interview in Brunei, where he arrived on Tuesday for a two-day meeting of Asian defense ministers.

The U.S. military is “ready to go,” Hagel said. Hagel spoke to his British and French counterparts on Tuesday and told the BBC that most leaders in the international community “have little doubt that the most base, human, international humanitarian standard was violated [by Syria] in using chemical weapons against their own people.”

Now there is little talk anymore within the administration of seeking a U.N. or NATO imprimatur for a retaliatory military strike against Syria.

“If action is taken, it probably won't be pursued through the U.N. or NATO,” a senior U.S. official told Defense One. “These aren't the only ways to undertake such action, and any response would be conducted pursuant to the law.”

Any U.N. Security Council approval would require Russia’s acquiescence, and Moscow has not shown signs it was ready to bend, even now. NATO has taken few steps to organize a mission into Syria, leaving the United States to create a new “coalition of the willing” from individual allies. Secretary of State John Kerry said Monday there was growing international support for military action against Syria. “This is about the large-scale, indiscriminate use of weapons that the civilized world long ago decided must never be used at all -- a conviction shared even by countries that agree on little else,” he said.

[Related: Defense One's full coverage and analysis on the events in Syria]

Hagel spoke by phone on Tuesday with U.K. Secretary of State for Defense Phillip Hammond and French Minister of Defense Jean-Yves Le Drian. France has been pushing to respond with “force” against the Assad regime, saying “there must be a reaction” to the reports that Assad used chemical weapons in an attack outside Damascus last week.

"It is a problem that will be difficult. International law is defined by the United Nations, but at same time there are countries (on the council) that are blocking (military action), China and Russia have blocked and would probably block again, so it would be a problem,” French Foreign Minister Laurent Fabius told Europe 1 radio on Monday. “In certain circumstances we can bypass it, but international law does exist," he said. "The only one that is not on the table is to not do anything.”

In a statement, The Arab League is demanding "that all the perpetrators of this heinous crime be presented for international trials.” The statement, according to Reuters, also urged the U.N. Security Council to "overcome the differences among its members by taking the necessary ... resolutions against the perpetrators of this crime, for which the Syrian regime bears responsibility, and to end the violations and crimes of genocide that the Syrian regime has been carrying out for over two years.”

The Obama administration is expected to release a report, possibly this week, showing evidence that the Syrian government used chemical weapons against its people during an attack last week outside Damascus. Vice President Joe Biden said Tuesday there was “no doubt” that the Syrian government was behind the attacks. During a briefing on Tuesday, White House spokesman Jay Carney said all the evidence points to Syria.

"We have made clear that it is our firm assessment that the Syrian regime has maintained control of the stockpile of chemical weapons in Syria throughout this conflict. It is also the case that the Syrian regime has the rocket capacity to deliver the chemical weapons as they were delivered with repugnant results on Aug. 21 outside of Damascus," he said.

"So the deliberations that are taking place now and the options that are being considered by the president and his national security team are not around the question of whether or not chemical weapons were used in Syria on a significant scale, causing mass death and injury to innocent civilians -- to women and children. It is not around the question of whether or not the Syrian regime is responsible. It’s around the question of what is the appropriate response to this clear violation of international norms," Carney said.

Carney told reporters -- multiple times -- that Obama has not decided what response will be carried out and would not speculate about the legal basis behind any attacks. "I'm not going to make legal justifications for actions that haven't been decided upon," he said.