Department of Homeland Security Secretary Michael Chertoff yesterday said illegal immigration is a "severe and growing threat" and while it will take time to correct, the government has begun a campaign to secure America's borders. "Illegal migration ... undercuts the rule of law, it undermines our national security, and it imposes public safety and economic strains on our borders, states and communities," Mr. Chertoff said in a speech during the American Legislative Exchange Council's (ALEC) policy summit in Washington.