WASHINGTON — The United States must ensure that immigrants are fully included in the fabric of American society to prevent violent ideologies from taking root at home, Vice President Joe Biden said Tuesday as he opened a White House summit on countering extremism and radicalization.

Joining local elected officials, community leaders and religious figures, Biden portrayed the U.S. as far better positioned than Europe, thanks to what he called America’s successful record at cultural integration. He said societies must offer immigrants an “affirmative alternative” to extremism, cautioning that military force alone could not address the threat.

Across the Atlantic, deadly terrorist attacks in France, Belgium and Denmark have left Europeans feeling vulnerable to the type of violent ideology promoted by the Islamic State group and once thought to be confined mostly to the Middle East and North Africa.

“National security flows from a sense of community,” Biden said, adding that the most important lesson the U.S. can learn is that “inclusion counts.”

The White House has sought to use the three-day conference in Washington to stir a sense of urgency about the challenge of preventing home-grown terrorism and the radicalization and recruitment of Americans, particularly disaffected young people. Yet it comes as the Obama administration has struggled to match its stated strategy for fighting IS and other Islamic extremist groups with the realities on the ground in Libya, Yemen and other Mideast hotspots.