sentences:  Construction on all 18 silos at the six launch complexes was completed by 4 August 1961.On 18 April 1962, Headquarters SAC declared wing's the 724th Squadron operational, and two days later the first Titan Is went on alert status.A month later, the sister 725th Strategic Missile Squadron, which had replaced the 849th Strategic Missile Squadron, declared it had placed all nine of its Titan Is on alert status, which marked a first in Strategic Air Command.