The primary advantage of a zero-length launch system is the elimination of the historic dependence on vulnerable airfields to facilitate air operations. In the event of a sudden attack, air forces equipped with such systems could field effective air defenses and launch their own airstrikes even with their own airbases having been destroyed by an early nuclear attack. Although launching aircraft using rocket boosters proved to be relatively trouble-free, a runway was still required for these aircraft to be able to land or else be forced to crash. The mobile launching platforms also proved to be expensive to operate and somewhat bulky, typically making them difficult to transport. The security of the mobile launchers themselves would have been a major responsibility in and of itself, especially in the case of such launchers being equipped with nuclear-armed strike fighters.