The United States has been involved on the battlefield post-9/11 in Iraq and Afghanistan. Military members have also seen time in Syria and Libya.

Some worry the fight with the so-called Islamic State could extend the country even further, but the U.S. hasn’t been involved in what’s labeled a world war in more than 70 years.

Strategist P.W. Singer spoke about what our leaders should be preparing for. Singer is a senior fellow with the New America Foundation. He’s also involved with the Center on the Future of War at Arizona State University.