By early 1971, North Vietnamese troop strength in the Base Area 604 area was estimated by U.S. intelligence at 22,000 men: 7,000 combat troops, 10,000 personnel in logistical and support units, and 5,000 Pathet Lao, all under the command of the newly created 70th Front.
There were differing views on what the expected reaction of PAVN to the offensive might be.
General Abrams believed that unlike Cambodia, the North Vietnamese would stand and fight for the Laotian Base Areas.
As early as 11 December he had reported to Admiral McCain that:
strong infantry, armor, and artillery formations were in southern Laos...formidable air defenses were deployed...the mountainous, jungle-covered terrain was an added liability.
Natural clearings for helicopter landing zones were scarce and likely to be heavily defended.
The bulk of the enemy's combat units were in the vicinity of Tchepone and PAVN could be expected to defend his base areas and logistics centers against any allied operation.

A prescient CIA study released in December 1970 echoed Abrams' concerns and was supported by a 21 January memorandum which "was remarkably accurate with respect to the nature, pattern, and all-out intensity of [PAVN] reactions."

MACV intelligence, on the other hand was convinced that the incursion would be only lightly opposed.
Tactical air strikes and artillery preparations would neutralize the estimated 170 to 200 anti-aircraft artillery weapons believed to be in the area, and the threat posed by PAVN armored units was considered minimal.
North Vietnamese reinforcement capability was set at 14 days by two divisions north of the DMZ, and it was hoped that diversionary operations would occupy them for the duration of the operation.
Unfortunately, when North Vietnamese reinforcements did arrive, they did not come from the north as expected, but from Base Area 611 and the A Shau Valley to the south, where eight regiments, all supported by organic artillery units, were within two weeks marching range.

The North Vietnamese were expecting some sort of operation as early as 26 January when the text of an intercepted radio message read "It has been determined that the enemy may strike into our cargo carrier system in order to cut it off...Prepare to mobilize and strike the enemy hard.
Be vigilant."

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.
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 (16.744°N 106.493°E) while the 21st Ranger Battalion moved into Ranger South (16.736°N 106.472°E).
These outposts were to serve as tripwires for any communist advance into the zone of the ARVN incursion.
Meanwhile, the 2nd Airborne Battalion occupied Fire Support Base (FSB) 30 (16.696°N 106.486°E) while the 3rd Airborne Brigade Headquarters and the 3rd Airborne Battalion went into FSB 31 (16.715°N 106.426°E).
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.

The mission of the ARVN central column was to advance down the valley of the Se Pone River, a relatively flat area of brush interspersed with patches of jungle and dominated by heights to its north and the river and more mountains to the south.
Almost immediately, supporting helicopters began to take fire from the heights, which allowed PAVN gunners to fire down on the aircraft from pre-registered machine gun and mortar positions.
Making matters worse for the advance, Route 9 was in poor condition, so poor in fact that on
By early 1971, North Vietnamese troop strength in the Base Area 604 area was estimated by U.S. intelligence at 22,000 men: 7,000 combat troops, 10,000 personnel in logistical and support units, and 5,000 Pathet Lao, all under the command of the newly created 70th Front. There were differing views on what the expected reaction of PAVN to the offensive might be. General Abrams believed that unlike Cambodia, the North Vietnamese would stand and fight for the Laotian Base Areas. As early as 11 December he had reported to Admiral McCain that:
strong infantry, armor, and artillery formations were in southern Laos...formidable air defenses were deployed...the mountainous, jungle-covered terrain was an added liability. Natural clearings for helicopter landing zones were scarce and likely to be heavily defended. The bulk of the enemy's combat units were in the vicinity of Tchepone and PAVN could be expected to defend his base areas and logistics centers against any allied operation.
A prescient CIA study released in December 1970 echoed Abrams' concerns and was supported by a 21 January memorandum which "was remarkably accurate with respect to the nature, pattern, and all-out intensity of [PAVN] reactions."
MACV intelligence, on the other hand was convinced that the incursion would be only lightly opposed. Tactical air strikes and artillery preparations would neutralize the estimated 170 to 200 anti-aircraft artillery weapons believed to be in the area, and the threat posed by PAVN armored units was considered minimal. North Vietnamese reinforcement capability was set at 14 days by two divisions north of the DMZ, and it was hoped that diversionary operations would occupy them for the duration of the operation. Unfortunately, when North Vietnamese reinforcements did arrive, they did not come from the north as expected, but from Base Area 611 and the A Shau Valley to the south, where eight regiments, all supported by organic artillery units, were within two weeks marching range.
The North Vietnamese were expecting some sort of operation as early as 26 January when the text of an intercepted radio message read "It has been determined that the enemy may strike into our cargo carrier system in order to cut it off...Prepare to mobilize and strike the enemy hard. Be vigilant."
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. 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 (16.744°N 106.493°E) while the 21st Ranger Battalion moved into Ranger South (16.736°N 106.472°E). These outposts were to serve as tripwires for any communist advance into the zone of the ARVN incursion. Meanwhile, the 2nd Airborne Battalion occupied Fire Support Base (FSB) 30 (16.696°N 106.486°E) while the 3rd Airborne Brigade Headquarters and the 3rd Airborne Battalion went into FSB 31 (16.715°N 106.426°E). 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.
The mission of the ARVN central column was to advance down the valley of the Se Pone River, a relatively flat area of brush interspersed with patches of jungle and dominated by heights to its north and the river and more mountains to the south. Almost immediately, supporting helicopters began to take fire from the heights, which allowed PAVN gunners to fire down on the aircraft from pre-registered machine gun and mortar positions. Making matters worse for the advance, Route 9 was in poor condition, so poor in fact that on
Operation Lam Son 719