America's biggest pro-Israel groups are throwing their weight behind President Obama's plan for U.S. military intervention in Syria. The American Israel Public Affairs Committee, known as AIPAC, said Tuesday that congressional authorization for strikes against Syrian President Assad's regime would ensure that what it called "barbarism on a mass scale" doesn't go unanswered.

In a statement it said military action would send a message to Assad's supporters -- Iran and Hezbollah -- that U.S. won't tolerate use of weapons of mass destruction.

The Anti-Defamation League also supports Obama.

Its statement cited "significant national security interests" at stake and said the U.S. has a moral imperative to act.

AIPAC wields significant influence in Congress, which is expected to vote on authorizing use of force against Syria.