The bipartisan group cited published reports about Russia's influence campaign, which aimed to sow discord during the 2016 presidential campaign, as well as the work of Vietnam Veterans of America, a Congressionally-chartered group that has monitored "suspicious" Facebook pages targeting vets.
"Online influence and psychological operations against trusted civilian community leaders like our nation's veterans are novel threats that demand law enforcement attention," the congressmen write in their letter to FBI Director Christopher Wray.
One fraudulent Facebook page called "Nam Vets" was taken down because of copyright infringement, according to the lawmakers.
A Facebook spokesperson confirmed to Fox News that the company has been in touch with the FBI on this issue.
In the wake of the 2016 election backlash, Facebook has significantly beefed up its efforts to combat coordinated inauthentic behavior, removing hundreds of pages tied to Russia and also Iran, while strengthening its overall detection and moderation systems around these issues.
The letter, which was signed by Reps. Gil Cisneros, D-Calif., Don Bacon, R-Neb., Ted Lieu, D-Calif. and Greg Steube, R-Fla., asks the FBI to provide answers to several questions, including whether the agency has contacted veterans service organizations about targeting from foreign entities and if the FBI will commit to meeting with veterans groups that have dealt with this topic.
"As you know, the FBI joined the intelligence community in its joint assessment of Russian interference in the U.S. political system -- a crucial piece of which was online influence operations 'that blend[ed] covert intelligence operations...with overt efforts by Russian Government agencies, state-funded media, third-party intermediaries, and paid social media users or 'trolls,'" they wrote.
Cisneros, a Navy veteran, told Stars and Stripes that he asked for an investigation "in order to identify and dismantle these cyber threats before they cause harm."