President Obama said the United States was ready and "should take military action against Syrian targets," but said he would seek congressional authorization to carry out an attack on Syrian President Bashar Assad's regime.

In a Rose Garden press conference Saturday afternoon, Obama outlined the importance of retaliating against what U.S. intelligence experts say was a chemical attack by Assad's regime that killed more than 1,400 people, including 426 children.

"This attack is an assault on human dignity," Obama said with Vice President Biden standing by his side. "It also presents a serious danger to our national security."

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Obama said congressional leaders have agreed to schedule a debate and vote when they return to session. They are scheduled to return from their summer recess on Sept. 9. He urged members to put politics aside and vote in support of a strike.

"Some things are more important than partisan differences or the politics of the moment," he said. "Today I'm asking Congress to send a message to the world that we are united as one nation."

The president's remarks came hours after U.N. experts finished collecting samples from last week's alleged chemical weapons strike outside Damascus. The inspectors had left the country bound for the Netherlands.

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The U.N. experts were working to confirm the apparent chemical weapons attack near Damascus on Aug. 21, which U.S. intelligence reports say left 1,429 people dead, including 426 children. The inspectors now plan to test the samples taken from soil and the blood and urine of victims.

Obama's statements also followed a parliamentary vote in Britain on Thursday that broke with its longtime U.S. ally in deciding against military action on Syria.

Obama urged the U.S. Congress to show more forcefulness in their vote, saying the United States has a moral obligation to show that "we do what we say" and that "right makes might and not the other way around."