He says the new fight must avoid what he calls mistakes of the past. Obama says more nations are joining a coalition against the extremists.
In his weekly radio and Internet address, Obama says, "This can't be America's fight alone."
In the Republican address, a candidate for a House seat from Arizona, Andy Tobin, says he's running for Congress because his state is under attack from the federal government. He cites regulations and havoc from Washington and says it is a problem everywhere.