Anchored by Jake Tapper, The Lead airs at 4 p.m. ET on CNN.
What's the U.S. plan on Russia's "all out" invasion? Plus, a look at the strategy for fighting ISIS.
(CNN) – Searchers say pulse signals detected in the Indian Ocean provide the best hope so far for finding Malaysia Airlines Flight 370.
But the search will be affected by the equipment being used, and the continuing effort to locate a debris field.
CNN safety analyst David Soucie, author of "Why Planes Crash, and David Stupples, professor at City University London, discuss.