 The minesweepers fueled on occasion at a South Vietnamese fueling station located near the fishing port (Da Nang) and took on evidence from CIA operatives which allegedly tended to prove that China and Russia were supplying the Viet Cong with weapons and other material.Occasionally, usually between midnight and 3 a.m., DRVN gunboats would approach the minesweepers at high speed and then peel off and return to a DRVN naval base operating on an island north of the 30th parallel.The gunboats made threatening maneuvers but never actually attacked the minesweepers.