A Virginia man pleaded guilty Wednesday to terrorism charges for his efforts to provide material support to the Islamic State, according to the Department of Justice.

Lionel Williams, 27, of Suffolk, Va., attempted to send money on two separate occasions to an individual he believed was an ISIS financier, according to a statement of facts filed with the plea agreement. The individual was actually an undercover FBI employee, who told Williams his donation had assisted purchasing a rocket-propelled grenade.

In response to this news, Williams said, "Praise be to Allah, and Allah is the Greatest."

Court documents reveal Williams' interest in ISIS has existed since 2014, and he purchased an AK-27 assault rifle on Dec. 3, 2015 — immediately following the San Bernardino terrorist attack.

Additionally, Williams' social media accounts show his support for ISIS. In March 2016, he posted his support for ISIS and expressed his desire for ISIS to take over the U.S. Furthermore, he said he would decapitate law enforcement agents that might have him under surveillance.

In 2016, Williams also shared plans of a martyrdom operation with a woman outside the U.S. and requested more information about specific types of AK-47 ammunition from an FBI confidential source. He told the FBI employee that the information was for a "local" operation.

Williams was arrested after this incident and consequently charged. He told agents he supported ISIS and said he was involved with a "holy war" after he was arrested.

Williams faces a statutory maximum of 20 years in prison when he is sentenced on Dec. 20.