The boyband has hired the bodyguards for their upcoming US tour, reported Sun Online.
Beefed-up security to combat crazed fans also includes men from the troops who had served in Iraq.
Tour chiefs fear Liam Payne's recent split from dancer Danielle Peazer will make him the prime target for female fans.
Their US tour kicks off from Florida on June, 13 but the fan websites have already posted details of the boyband's hotels.
"Liam becoming single has made things even more fraught. Some of the security staff have worked with Obama and in war zones," said a source.