KAILUA, Hawaii, Dec 28 (Reuters) - President Barack Obama on Monday vowed to track down those behind an attempt to bring down a U.S. passenger airline on Christmas Day as he announced stepped-up measures to ensure U.S. flight safety.
"We will not rest until we find all who were involved and hold them accountable," Obama said, interrupting his year-end vacation to assure Americans that his administration was doing all it could to ensure security after a Nigerian student managed to smuggle explosives onto a Detroit-bound flight.
(Reporting by Jeff Mason, editing by Patricia Zengerle)