 After the 8 May attack, recognizing that the PAVN were using the DMZ as a sanctuary for attacks into I Corps, Washington lifted the prohibition on US forces entering the DMZ and MACV authorized the III Marine Amphibious Force (III MAF) to conduct combat operations into the southern half of the DMZ.From 13–16 May, 1/9 Marines cleared Route 561 from Cam Lo to Con Thien fought a well-entrenched PAVN force south of the base.The PAVN subsequently withdrew into the DMZ.