Washington DC - A citizen of Afghanistan has been charged for allegedly conspiring to conduct a terrorist attack on US soil, the US Department of Justice said on Tuesday.

The department said the man (27), who resided in Oklahoma, planned to carry out an attack on the day of the presidential election, November 5.

"As charged, the Justice Department foiled the defendant’s plot to acquire semi-automatic weapons and commit a violent attack in the name of ISIS on US soil on Election Day," Attorney General Merrick Garland, using an acronym for extremist militia organization Islamic State.

"We will continue to combat the ongoing threat that ISIS and its supporters pose to America's national security, and we will identify, investigate, and prosecute the individuals who seek to terrorize the American people."

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As part of the plot, the defendant allegedly took steps to liquidate his family's assets, resettle members of his family overseas, and acquire AK-47 assault rifles and ammunition, the department said.

It said the man, and a juvenile, were arrested on Monday after they purchased, received, and took possession of two AK-47 assault rifles, 10 magazines, and 500 rounds of ammunition from undercover FBI agents.

The man is being charged with attempting to provide material support and resources to a designated foreign terrorist organization. If found guilty he would face a maximum sentence of 20 years in prison.

He has also been charged with receiving a firearm to be used to commit a felony or a federal crime of terrorism, which carries a maximum prison sentence of 15 years, if convicted.