Chevron Shape craft trails formation of military jets across Sierra Nevada Mountains.On the evening of August 8, 2001 at apx. 10:15 pm my girl friend and I were looking at the night sky while camping at the north shore of Saddlebag Lake (elevation: 10,000 feet)-- located apx. 7 miles North of the Tioga Pass entry gate to Yosemite National Park, and apx.15 miles West of the town of Lee Vining, CA. The sky was clear,and moonless. We witnessed a formation of three "military fighter jets", displaying normal navagational lights, and flying at apx. 15,000 feet on a due West heading. We clearly heard the familier sound of their engines. Trailing the formation of fighter jets (at apx. the fighter jets 8 o'clock position)was a quite large "Chevron Shaped Object". We were able to see shapes quite well, as the OBJECT and the Jets were being backlit by the starlight of the "Milkey Way". Using the fighter jets size as reference, we estimated the OBJECT size to be 100 yards from tip-to-tip of its Chevron Shape. The OBJECT had three "white colored" lights -- one at the apex, and one at each end(or wingtip)of the "Chevron Shape". The OBJECT did not display ANY OTHER navigational lights. The OBJECT matched the jets air speed and seemed to move more like a glider than a powered aircraft. The OBJECT and the jets were observable for apx. 2 minutes. My girl friend and I are very familier with the air traffic in the Tioga Pass area of Yosemite. There is a major East-West commercial air traffic corridor that follows the trace of Tioga Road (HWY 120). The steady stream of air traffic is quite familier and predictable in this area. Military flights are also quite common in this area. The flight path of the OBJECT and the three military jets we observed was south of and parallel to the commercial air corridor that follows Tioga Road. Neither one of us have ever seen an "aircraft" the size of the OBJECT we saw. Both of us are highly trained and experienced professionals (Health Care and Photojournalism) with keen observational skills and are certain of our observations that evening.