Though he announced his decision to bypass the UN Security Council, which he alleged has been paralysed, Obama said he would seek the US Congress' approval for his administration to take military action against the Assad regime for using chemical weapons against internationally-established norms.
But Obama did not announce a time frame for the action.
In an address to the nation from the Rose Garden of the White House, Obama accompanied by Vice President Joe Biden, urged Congress to debate and vote for his decision on military action against the Syrian regime.
"After careful deliberation, I have decided the United States should take military action against Syrian targets. I'm confident we can hold the Assad regime accountable for their use of chemical weapons," Obama said.
"This attack is an attack on human dignity and it risks making a mockery of the global prohibition of the ban on chemical weapons," he said.
"In a world with many dangers, this attack must be confronted. The US should take military action," he asserted.
"I will seek authorisation for the use of force by the representatives of the US people, the members of the US Congress," he said urging lawmakers to put aside their differences to vote for military action against Syrian regime.
"Some things are more important than partisan differences or the politics of the moment. Today I'm asking Congress to send a message to the world that we are united as one nation," he said.
Presenting his case to the American people and the Congress, Obama said the US "cannot and must not turn a blind eye" to what happened in Damascus. "America must keep its commitments," he said.
Defense Secretary Chuck Hagel immediately came out in support of Obama.
Hagel, "supports" Obama's decision on "congressional authorisation for use of force in Syria, agrees we cannot turn blind eye to Syrian chemical weapons use," his spokesman George Little, said.
The remarks by Obama came a day after his administration released its intelligence assessment blaming the Assad regime for using chemical weapons against its own people that killed 1,429, including at least 426 children.
Obama said yesterday that the US would not send its "boots on the ground", but is looking for a "limited" military action, with the sole purpose of holding Assad's regime accountable for the use of chemical weapons, which is in gross violations of the well-established international conventions.
Later today, Senior administration officials were scheduled to hold unclassified conference calls with senators as part of their effort to continue consultations the Syrian regime's alleged use of chemical weapons during the August 21 attack.
National Security Advisor Susan Rice; Secretary of State John Kerry and Defense Secretary Chuck Hagel were among others set to attend the briefing.
Top Republican Senator John Cornyn demanded that Obama should take Congressional approval for any military action against Syria.
"Before any military action is taken in Syria, the president should call Congress back into session and ask for a vote on the authorisation to use force," he said.