'Enough threats have come in that the network is on higher security alert,' the source said.
'They have a huge public building with a museum and 1,600 people working.'
The movie will premiere two days before the November 6 election, drawing fire from critics on the right who have accused National Geographic of being partisan.
But National Geographic Channel president Howard T. Owens told The Hollywood Reporter that the timing of Seal Team Six release was not politically motivated.
Instead, Owens said the premiere was set for November 4 to promote the channel's upcoming fall schedule.
The movie was produced by Harvey Weinstein, a major Obama supporter.
