A US Air Force veteran has been sentenced to 35 years in prison for trying to join terrorist organisation Isis in Syria.

Tairod Pugh, aged 49, of New Jersey was found guilty of trying to distribute material support to Isis. He was stopped by security officials at a Turkish airport in January 2015 and was discovered to be in possession of a laptop containing 180 jihadist videos, including footage of a beheading.

They are also found a map showing border crossings from Turkey to Syria and a letter in which Pugh told his Egyptian wife that he wished to become a martyr.

"I am a Mujahid. I am a sword against the oppressor and a shield for the oppressed. I will use the talents and skills given to me by Allah to establish and defend the Islamic State. There are only two possible outcomes for me: Victory or Martyr," the letter read.

Pugh, who declared that he was innocent in court, is the first person to be successfully prosecuted for an Isis-related offence in the US.

The Muslim convert served as an aircraft engineer in the US air force from 1986 to 1990 and worked as a military contractor in Iraq from 2009 to 2010. After leaving the armed forces, he worked as a civil aviation engineer in Kuwait.

Prosecutor Bridget Rohd said the defendant "turned his back on his country, and the military he once served, to attempt to join a brutally violent terrorist organization committed to the slaughter of innocent people throughout the world."

"This isn't about whether you're Muslim, or Christian or Jewish," Brooklyn federal judge Nicholas Garaufis told Pugh. "This is about whether you're going to stand up for your country, which has done so much for you, or betray your country. You've made your choice, sir. I have no sympathy."