Looking for His glorious appearing! Titus 2:13

Khaled Sharrouf left Australia to fight for the Islamic State group.

Los Angeles: The alleged Islamic State terror plot to kidnap and behead an Australian was partly responsible for the decision to ramp up security at US government buildings, according to a high-ranking congressman.

Mike Rogers, the chairman of the US House Intelligence Committee, told FOX News that 14 Australian IS recruits were "ready to go to Syria" at the time and "further their radicalisation".

But Mr Rogers said the recruits were told to stay in Australia. The senior Republican politician said the note back from IS said: "No, No. What we want you to do, stay in Australia. We want you to randomly kidnap people off the street, behead them, videotape it, send it to us for further propaganda."

Abdullah Elmir from Bankstown has also left Australia to fight with the Islamist fanatics.

On Tuesday, the Department of Homeland Security boosted security at 9500 federal buildings across the US. Mr Rogers linked the alleged IS Australian beheading plot and other intelligence to the security boost.

"They wanted to have a high-profile event in a Western country," he said.

"They wanted to show that they could reach out and strike a Western country, which is why we believe now you see all of this activity - Canada, the United States, across Europe, Germany, France, Spain, because they're actively working at trying to find an event that happens in a Western country that they can take credit for."