In 1965, President Lyndon Johnson decided to drastically, but quietly, increase America's commitment in South Vietnam (search) to combat the threat of communism.

And the public agreed. Polls showed that 80 percent of Americans supported helping South Vietnam.

The North was communist and allied with America’s Cold War (search) enemies, the Soviet Union and China.

Ho Chi Minh (search) ruled the North with a singular purpose — defeat the government in the South and create an independent, unified and communist Vietnam.

"The advance of communism had to be stopped," said Jim McInerney, who began his military career as a paratrooper in the 82nd Airborne.

And so, the United States launched Operation Rolling Thunder.

Learn more about Operation Rolling Thunder during the Vietnam War. Watch "War Stories with Oliver North" on Sunday at 8 p.m. EDT on the FOX News Channel.

"Rolling Thunder was an extraordinarily cautious bombing campaign. It reflected the caution of the guy who ran it, President of the United States Lyndon Johnson," said Wayne Thompson, author of “To Hanoi and Back.”

But White House orders forced the men flying these missions to fight with one hand tied behind their backs, inevitably costing American lives.

Roughly two-thirds of North Vietnam's imports came through the port of Haiphong, which was forbidden for two years to be bombed. Closing the port would have crippled the enemy, but White House restrictions allowed the supplies to keep flowing.

Pilots also were virtually forbidden from attacking surface-to-air missile sites, a rule that hindered U.S. efforts.

"It was a frustrating thing ... we knew we had to fight within these rules of engagement," said airman Dave Brog.

"The restrictions were so ridiculous," Jack McEnroe agreed.

Between 1961 and 1973, more than 3,000 aircraft were shot down or destroyed in Southeast Asia, and from March 1965 to October 1968, the last year of Rolling Thunder, Air Force, Navy and Marine airmen dropped one-half million tons of bombs over North Vietnam – impressive, but far from a triumph.

In December 1965 Johnson temporarily halted the Rolling Thunder raids, hoping Ho Chi Minh would agree to talks. Instead, the North used the bombing pause to improve defenses and hide targets. They also refused to disclose what pilots they held in captivity. Torture and interrogation were a fact of life for the U.S. prisoners of war.

"They … took me over, hung me by my feet for the entire day. Really horrible experience when your arm is all fractured up, you know. [It] was barbaric," airman Bud Day said.

By 1967, protests against the war began to grow in number and size. In November that year, Secretary of Defense Robert McNamara resigned.

Two months after his resignation, the enemy mounted an offensive in South Vietnam.

Fierce battles raged in cities across the country, including the capital, Saigon. Removed from the safety of their jungle sanctuaries, the Viet Cong and NVA were defeated.

But the military victory was lost in the court of public opinion, and President Johnson had had enough, too

"I shall not seek, and I will not accept, the nomination of my party for another term as your president," he said on March 31, 1968.

"He also announced that he was pulling back the bombing of North Vietnam," Thompson said.

After 2 1/2 years, more than one-half million tons of bombs dropped, 900 planes lost and more than 1,000 airmen killed, missing or captured, Rolling Thunder finally ended in October 1968.

In early 1973 the last American combat troops left Vietnam. Two years later the North Vietnamese army rolled into Saigon.

Some of the war’s few joyous moments came in February, March and April of 1973 with the release of 591 American POWs.

For the American airmen who flew during Rolling Thunder, one word describes their experience: frustrating. These well-trained, remarkably brave aviators were willing to fly through enemy skies swarming with anti-aircraft fire.

The foe they most feared? Indecision. Washington's vacillation and uncertainty in confronting a determined and ruthless enemy doomed Rolling Thunder before the first aircraft lifted off a runway or catapulted from the deck of a carrier.

Learn more about Operation Rolling Thunder during the Vietnam War. Watch "War Stories with Oliver North" on Sunday at 8 p.m. EDT on the FOX News Channel.

Click in the video box above to learn more about Operation Rolling Thunder.