why did Ben Franklin know what was happening

Randy goes to pick up Helen, Peyton, and Ben Franklin from the airport in the early hours of the morning and tells them what happened in the Mediterranean. The children are, by this point, hardened to war, so the news doesn't faze them. Back in Omaha, still waiting to hear anything from Moscow, Mark gets news of three unidentified submarines headed for the Atlantic coast. They decide to phone the president to get permission to use the nation's own nuclear weapons if necessary.