A ban on large carry-on electronics on some international flights lays bare a high-stakes scientific battle between militant groups and security chiefs that has already dramatically altered airline travel, especially since the September 2001 attacks in the United States.
Security experts say the decision to place devices bigger than a cellphone into checked bags on U.S.-bound flights from eight Middle East or North African states suggests Washington believes enough material can be packed in a laptop, usually disguised as its battery, to cause catastrophic damage.
Most experts agree today's ever-thinner smartphones make it harder to hide enough explosive to down a large aircraft, but that they can be used to detonate devices located elsewhere.