Mumbai-born Noshir Gowadia, 66, who has been in custody without bail since his 2005 arrest, showed no emotion as Chief US District Judge Susan Oki Mollway pronounced the punishment in Honolulu on Monday, according to media reports.
In August, a federal jury had convicted Gowadia of 14 counts, including conspiracy, communicating national defence information to aid a foreign nation, and violating the arms export control act. Prosecutors said Gowadia helped China design a stealth cruise missile to get money to pay the $15,000-a-month mortgage on his multimillion dollar home overlooking the ocean in Haiku on Maui.
They said Gowadia pocketed at least $110,000 from the sale of military secrets and showing his Chinese contacts how his stealth cruise missile design would be effective against US air-to-air missiles.
Gowadia's defence attorneys said it's true the engineer gave China the design for a stealth cruise missile exhaust nozzle but he based his work on unclassified, publicly available information. Gowadia's son has said his father plans to appeal.
The sentencing comes just weeks after China conducted a flight test of its new J-20 stealth fighter during a visit to Beijing by US Defence Secretary Robert Gates.
The Jan 11 flight was held at an airfield in Chengdu, home to the Chengdu Aircraft Design Institute and is a centre for Chinese fighter aircraft and cruise missile research and development, where prosecutors say Gowadia delivered an oral presentation on classified stealth technology in 2003.
Between 2003 and 2005 Gowadia made six secret trips into mainland China and exchanged numerous communications to help Chinese defence engineers design a cruise missile that is able to evade air-to-air, heat-seeking missiles, they said.
Gowadia helped design the propulsion system for the B-2 bomber when he worked at Northrop Corp., now known as Northrop Grumman Corp, between 1968 and 1986.
Gowadia moved from India to the US for postgraduate work in the 1960s and became a US citizen about a decade later. He retired from Northrop for health reasons in 1986, two years before the B-2 made its public debut.
Gowadia moved to Maui in 1999 from the US mainland where he had been doing consulting work after retiring from Northrop.