US Navy will modify its Quickstrike naval mines so that they can disable enemy mines and clear a safe passage for its ships. The mine is usually dropped from a fighter aircraft. As it falls, air pressure and impact with the water arm the warhead, causing it to detonate when a ship approaches. The Navy proposes to change the triggering device so that the mine responds only to a pulsed magnetic signal. If a US ship suspects enemy mines ahead, aircraft will blanket the area with the modified Quickstrikes and then transmit a particular coded magnetic signal. All US mines will explode simultaneously, creating a shock wave strong enough to destroy the enemy mines (New Scientist , Vol 156, No 2109).