In 2008, a CIA analyst named "Ron Pandolfi" signed off on the declassification of the technology in a documented that he signed, here : https://fas.org/irp/agency/dod/jason/gravwaves.pdf
Pandolfi testified before the senate in 1998 in regards to the Chinese stealing U.S. technology:
https://www.washingtonpost.com/wp-srv/politics/special/campf...
The US patent office rejected the Navy's patents initially, then signed off on them after the Navy protested that China was working on something similar. Details here : https://www.thedrive.com/the-war-zone/28729/docs-show-navy-g...