Turkey is threatening to cancel the $4 billion purchase of AH-1Z King Cobra combat helicopters if the US does not allow it to use mission computers it plans to develop by itself. The US insists that the Turkish computers would compromise performance and flight safety. Turkey insists that its computers not only will do the job, but must be used as the AH-1Z is a unique configuration with different weapons than the US Marine versions. The Turks have demanded that the US agree to the computer swap by 1 August or it will take its checkbook elsewhere.--Stephen V Cole