 Low altitude drops during day and night did not do the job, so by May 2, the USAF began using High Altitude Low Opening (HALO) techniques.With far greater success, this method of resupply was utilized until June 25, when the siege was lifted and aircraft could land at An Lộc.Over the entire course of the resupply effort, the garrison recovered several thousand tons of supplies—the only supplies it received during the siege.