A month later, at the end of April, the US and Army of the Republic of Vietnam (ARVN) tried again. The initial ARVN attack of the Cambodian Campaign was launched by ARVN and US ground forces, which attempted to "clean out the sanctuaries." PAVN/NLF forces, however, had already been evacuated on March 19. COSVN and its sub-divisions had already withdrawn to the Kratié area and successfully avoided destruction. A marked reduction in radio traffic and transmitter power also made them difficult to place accurately at their new location, despite close 24-hour monitoring.