*Washington, US - US Navy Submarine test launches four nuclear capable missile to validate performance. *
US submarine tested four life-extended Trident II D5 missiles to validate their performance, the US Navy said in a statement on Friday.
Two tests were conducted by USS Nebraska on Wednesday and Friday respectively off the coast of Southern California, the statement said, adding all tests occurred before sunrise, the Xinhua news agency reported.
The primary goal of the tests were "to validate performance expectations of the life-extended Trident II strategic weapon system," the statement said.
The Trident II strategic weapon system, originally designed with a life span to 2024, recently underwent a life extension that will keep it operational through the late 2040s.