Detached from duty at Majuro on 13 June, "Burden R. Hastings" headed via Eniwetok for Pearl Harbor, proceeding independently. At 0250 on 16 June, the warship's SL radar picked up a surface contact 10 miles away that showed no IFF (Identification Friend or Foe) signal. The small "pip" on the radar screen indicated either a surfaced submarine or a small craft, so the captain decided to close range to and challenge the stranger visually. "Burden R. Hastings" proceeded ahead through the moderate sea while her quarry moved at . The destroyer escort rang up to close range and went to General Quarters. At 0337, when the two ships were 5,000 yards apart, "Burden R. Hastings" challenged thrice with an Aldis lamp but received no reply. She then fired four star shells in an effort to illuminate; but, after the second burst, radar plot reported that the "pip" had disappeared from the screen.