Washington: Former US defence secretary Robert McNamara, considered the architect of Vietnam war, died on Monday. He was 93.

McNamara died at his home, said his wife, Diana. She said he had been in failing health for some time.

McNamara was fundamentally associated with the Vietnam War, dubbed "McNamara's war," the only American war to end in withdrawal.

Known as a policymaker with a fixation for statistical analysis, McNamara was recruited to run the Pentagon by then-president John F. Kennedy in 1961.

He stayed seven years, longer than anyone since the job's creation in 1947.

His association with Vietnam became intensely personal. Even his son, as a Stanford University student, protested against the war while his father was running it.

At Harvard, McNamara once had to flee a student mob through underground utility tunnels.

Critics mocked McNamara mercilessly" they made much of the fact that his middle name was "Strange."

He told Time magazine in 1991 that he did not think the bombing of North Vietnam—the greatest bombing campaign in history up to that time—would work but he went along with it "because we had to try to prove it would not work, number one, and (because) other people thought it would work."