The North Vietnamese pulled off some pretty impressive operations of their own to counter our Operation Linebacker:
The American attacks were, basically, a war plan first proposed in 1965 and rejected out of hand by LBJ. (Indeed, when the Joint Chiefs raised the issue, LBJ, who wore a fraudulent Silver Star for nonexistent WWII heroism, abused them at length, and SecDef McNamara showered them with the sort of contempt only a Harvard man who knows deep down he’s wrong can generate). US air and naval air forces would drop the bridges and close the choke points in the Vietnamese rail network, and aircraft would mine North Vietnam’s crucial harbors. Losing rail and sea transport, and having road transport constricted, wouldn’t completely choke North VIetnam’s war machine, but it would deprive it of air defense, which depended on large machines that had to come from abroad — radars, missiles and fighters. A first strike would disable the North Vietnamese Air Force on the ground.
The North Vietnamese and their Russian patrons had excellent sources in the US Government and had plenty of advance warning of the “sudden” attack. But with facilities like ports, airfields, and railway bridges to defend, there wasn’t that much they could do. At the end of Day One, the USAF confidently reported that the North Vietnamese Air Force wasn’t flying any more.
But the USAF was wrong, because the NVAF went into special-operations mode. Leveraging technology, daring, and secrecy, on the eve of the US raids many of the air force’s MiG-17 and MiG-21 fighters were airlifted — sling loaded — by Mi-6 helicopters. Russia had developed this capability in order to disperse their air defense forces prior to any future nuclear war, and they didn’t mind sharing the concept with their Vietnamese satellite. The gigantic cargo helicopters took the jets to austere, improvised airfields — firm farm fields, stretches of straight road — whence they would launch against US sorties. To do this they depended on a capability that had been developed, but mostly abandoned, by the WWII German and then the US Air Forces — rocket assisted take-off. Once again, Russia maintained this capability to retain a fighter force in the event of almost certain wartime attacks on airfields — attacks like the ones that had opened the German attack on Russia in 1941. The strap-on, drop-off rocket pods let a runway-loving turbojet fighter blast off almost like a space rocket, using a minimum stretch of ground. The aircraft would then recover to Phuc Yen airfield.
Here the NVAF were doing some smart, asymmetrical things that leveraged their capabilities and the US’s limitations. US ROE did not allow helicopters to be engaged at night, granting invulnerability to the most vulnerable evolution in the NVA plan. The civilian side of dual-purpose Phuc Yen was likewise off limits to US target planners.
It wasn’t enough to do much more than slow down the USAF though.