Washington DC, Nov. 14 -- US Homeland Security Secretary Markwayne Mullin on Friday (local time) said that there is no indication that a national security threat was behind the nationwide ground stop imposed across American airports following a telecommunications outage, seeking to distinguish the disruption from the September 11, 2001 attacks.

"This isn't the same comparison to 9/11," Mullin told reporters outside the White House, while assuring them that all flights had been accounted for and passengers were safe.

Mullin said authorities currently had no reason to believe the communications failure was linked to a threat against the United States, although he did not rule out any possible cause, including a cyberattack.

"There is no ...