MARIUPOL, Ukraine – An American nuclear scientist, and designer of sensitive technology found in dozens of laser-guided weapons systems used by the U.S. military, is actively being rescued from Russian-occupied territory deep in Ukraine after being hunted by Russian forces for months.

John Spor, a Texas native and founder of Texas Photonics Inc., had been living in Mariupol, Ukraine, when the city was attacked and occupied by invading Russian forces in February.