continued and so the US Government initiated a study that discovered that the red wasn't the issue since color couldn't be determined from a distance anyway, but the shape could be. After trying out several variations including an oblong roundel with two stars, they arrived at using white bars flanking the sides of the existing roundel, all with a red outline, which became official in June 1943. This still wasn't entirely satisfactory and at least one operational unit refused to add the red, resulting in bare white bars on the existing star roundel. The red outline was then replaced with a blue outline whose color exactly matched the round blue field that held the star in September 1943. On US Navy aircraft painted overall in gloss midnight blue starting in 1944, the blue color of the roundels was similar to midnight blue, so the blue portion was eventually dispensed with and only the white portion of the roundel was painted on the aircraft. In the Pacific Theater, some British Commonwealth aircraft in service with the British Pacific Fleet, and Royal New Zealand Air Force, as with Lend Lease Chance Vought F4U Corsairs, began to officially sport the white "bars" as a more-or-less "universal" symbol on Allied aircraft opposing the Japanese, while also eliminating the red center of the roundels they used for the same reason the United States already had. Cold War (1945-1991) to present In January 1947, single bisecting, lengthwise-running red bars, one per side, were added within the existing white bars on both USN and USAAF aircraft – both replacing the old center red circle, and restoring the official presence of a red device in the insignia, much as with the red stripes of the American flag – and in September of the same year, the United States Army Air Forces (USAAF) became an independent service and was renamed the United States Air Force (USAF). In 1955 the USN would repaint all its aircraft from midnight blue to light grey over white and would use exactly the same roundel as the USAF again. Since then there have been some minor variations, mostly having to do with low-visibility versions of the star and bars roundel. Air superiority F-15s eliminated the blue outline in the 1970s, and later some aircraft replaced the blue and red with black or a countershaded color, or used a stencil to create an outlined "low-visibility"