President Obama: 'This is not Afghanistan'

WASHINGTON -- The leaders of both parties in the House of Representatives emerged from a White House meeting to endorse U.S. military action against Syria, with House Speaker John Boehner saying only the United States has the "the capability and capacity" to respond to the use of chemical weapons. House Minority Leader Nancy Pelosi added that Washington must respond to actions "outside the circle of civilized human behavior."

(CNN) -- Working to persuade Congress to support a U.S. attack on Syria, President Barack Obama vowed Tuesday that the military plan would deliver important results while keeping the United States out of a larger war.

"This is not Iraq, and this is not Afghanistan," Obama told reporters before a meeting with lawmakers.

"This is a limited, proportional step that will send a clear message -- not only to the Assad regime, but also to other countries that may be interested in testing some of these international norms -- that there are consequences."

The United States, along with NATO and several other countries, blames Syrian President Bashar al-Assad's regime for a chemical weapons attack that's believed to have killed more than 1,000 people -- including, Obama said Tuesday, more than 400 children.

"This norm against using chemical weapons -- that 98 percent of the world agrees to -- is there for a reason, because we recognize that there are certain weapons that, when used, can not only end up resulting in grotesque deaths, but also can end up being transmitted to non-state actors, can pose a risk to allies and friends of ours like Israel, like Jordan, like Turkey," Obama said.

Obama said failing to punish Syria would send "a message that international norms around issues like nuclear proliferation don't mean much," he added.

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