New York air traffic controllers receive threat of a plane crashing into the Capitol on Wednesday

The audio of the threat, obtained by CBS News, refers to Qassem Soleimani, the Iranian general and terrorist who was killed in 2019 in a US drone strike. Iranian officials have promised retaliation for the targeted assassination, and the threat to the air traffic controllers was made on the one year anniversary of Soleimani's death.

Congress convened in the Capitol on Wednesday to count the votes of the Electoral College to certify the results of the 2020 Presidential election.

President Trump ordered the strike that killed Soleimani, the head of the Islamic Revolutionary Guard Corps' elite Quds Force, which itself has been a designated terror group since 2007, as well as other military officials at Baghdad International Airport.

Soleimani was the head of the Iranian and Iranian-backed forces which carried out operations that killed American troops. According to the US State Department, 17 percent of all deaths of American personnel in Iraq from 2003 to 2011 were organized by Soleimani.

According to CBS, "the government does not believe the warning of an attack is credible and it is being investigated as a breach of aviation frequencies."

Experts have told CBS that the intrusion is "concerning because it could affect the instructions pilots get about how and where planes fly."

Sources told CBS that a message was sent to air traffic controllers on Tuesday "reminding them that any threat or plane deviating from its flight path should be reported immediately."

The FBI has not commented on the threat other than saying that it takes "all threats of violence to public safety seriously." The Federal Aviation Administration told CBS they are in contact with law enforcement.