The tactical air strikes that were to precede the incursion and suppress known anti-aircraft positions were suspended two days prior to the operation due to poor flying weather. On 6 February a U.S. Navy A-6 Intruder accidentally bombed the 8th Airborne Battalion near the border, killing seven ARVN and destroying an APC. After a massive preliminary artillery bombardment and 11 B-52 Stratofortress missions, the incursion began on 8 February, when a 4,000-man ARVN armor/infantry task force consisting of the 3rd Armored Brigade and the 1st and 8th Airborne Battalions, advanced west unopposed along Route 9. To cover the northern flank, ARVN Airborne and Ranger elements were deployed to the north of the main advance. The 39th Ranger Battalion was helilifted into a Landing Zone (LZ) known as Ranger North () while the 21st Ranger Battalion moved into Ranger South (). These outposts were to serve as tripwires for any PAVN advance into the zone of the ARVN incursion. Meanwhile, the 2nd Airborne Battalion occupied FSB 30 (). At 16:55 U.S. helicopter gunships attacked a suspected PAVN target 2km east of the planned FSB 31 (), causing numerous secondary explosions and starting a huge fire which lasted until the following morning. Following this attack the 3rd Airborne Brigade headquarters and the 3rd Airborne Battalion landed and occupied FSB 31 unopposed. Troops of the 1st Infantry Division simultaneously combat assaulted into LZs Blue, Don, White and Brown and FSBs Hotel, Delta and Delta 1, covering the southern flank of the main advance.