In a 9-1-1 call shortly after the shooting began, Mateen swore allegiance to the leader of the Islamic State of Iraq and the Levant (ISIL), Abu Bakr al-Baghdadi, and said the shooting was "triggered" by the U.S. killing of Abu Waheeb in Iraq the previous month. He later told a negotiator he was "out here right now" because of the American-led interventions in Iraq and in Syria, and that the negotiator should tell the United States to stop bombing ISIL.

Initial reports said Mateen may have been a patron of the nightclub and used gay dating websites and apps, but Federal Bureau of Investigation (FBI) officials said they have not found any credible evidence to substantiate these claims. The Central Intelligence Agency (CIA) also conducted an investigation and said it found no links between ISIL and Mateen.

The worst mass shooting in U.S. history, which left at least 49 people dead and more than 50 wounded, has been described as both a terror attack and a hate crime by leaders and experts.

In a riposte to the attack, Twitter user @norlicious of Sweden posted pictures of herself kissing other women, saying "because our rights aren't a debate issue."

All of the "terrorist attacks" of the past several decades have been false flag attacks, that were falsely blamed on Muslims, but the attacks were actually perpetrated by agents of the US Government and its allies.