GOC post spotted target, confirmed by ADC radar, followed by F-47 fighter interception of a 6-8-inch white blinking light which made ramming attacks on the F-47 from 10,000 to 27,000 feet.

One object, about 6 inches across, was observed by over three military witnesses and radar near a nuclear test site for over 18 minutes.

Ruppelt's account:

On June 21, 1952, at 10:58P.M., a Ground Observer Corps spotter reported that a slow-moving craft was nearing the AEC's Oak Ridge Laboratory, an area so secret that it is prohibited to aircraft. The spotter called the light into his filter center and the filter center relayed the message to the ground control intercept radar. They had a target. But before they could do more than confirm the GOC spotter's report, the target faded from the radarscope.

An F-47 aircraft on combat air patrol in the area was vectored in visually, spotted a light, and closed on it. They "fought" from 10,000 to 27,000 feet, and several times the object made what seemed to be ramming attacks. The light was described as white, 6 to 8 inches in diameter, and blinking until it put on power. The pilot could see no silhouette around the light. The similarity to the Fargo case was striking.

...In the case involving the ground observer and the F-47 near the atomic installation, we plotted the winds and calculated that a lighted balloon was right at the spot where the pilot encountered the light.

Google map of this location.