WASHINGTON – There are no specific or credible security threats
against the United States known to law enforcement heading into the Fourth of
July weekend, according do a government document seen by Reuters and three
sources briefed on the matter.

The sources, who asked to speak on the condition of anonymity,
said there would be increased vigilance and heightened awareness across law
enforcement to keep Americans safe as they celebrate the nation’s Independence
Day.

An internal briefing document shared with government officials and
seen by Reuters called for the Department of Homeland Security to be on alert
following recent attacks, such as the mass shooting in Orlando, Florida, on
June 12, and calls from Islamic State supporters for attacks in the Western
Hemisphere.

The absence of known threats does not ensure safety. There were
no threats known before the Orlando massacre, in which a gunman who pledged
himself to Islamic State killed 49 people in the largest mass shooting in
modern U.S. history.

The document said mass transit systems are particularly
vulnerable to attack. It also said an attack over the U.S. Independence Day
holiday would garner media attention that would further the Islamic State’s
propaganda efforts.

There
was no mention in the document of the attack that killed 42 people at
Istanbul’s airport on Tuesday.