Key US missile defence test to go ahead

Delayed by bad weather for a second consecutive day, the US Defence Department tonight hopes to stage one more successful test of its missile defence system.

Some critics say the programme is too simplistic to reveal how well the United States would cope with an actual missile attack.

The fifth test of the prototype missile defence system - delayed by high winds on Saturday and Sunday - has been rescheduled for tonight.

The plan calls for a modified intercontinental ballistic missile carrying a mock warhead to be launched from a Californian air force base and head over the central Pacific Ocean.

Twenty minutes later an interceptor rocket would roar into the night sky from Kwajalein Atoll, home in on the target with the help of a radar in Hawaii, and ram into the mock warhead 144 miles into space.

The device that actually hits the warhead is known as a ‘‘kill vehicle,’’ a 120 pound, 55 inch long device that separates from the rocket booster and seeks out the target using its on-board infrared sensor.

Of the first four attempts to intercept a mock warhead in space, two succeeded and two failed. Each intercept test costs about £70m.