Question remains where Saudi Arabia gained the technical know-how to build such a facility. A military base deep inside Saudi Arabia appears to be testing and possibly manufacturing ballistic missiles, experts and satellite images suggest, evidence of the type of weapons programme it has long criticised its arch-rival Iran for possessing. Further raising the stakes for any such programme are comments by Saudi Arabia's powerful Crown Prince Mohammed bin Salman, who said last year that the kingdom wouldn't hesitate to develop nuclear weapons if Iran does. Ballistic missiles can carry nuclear warheads to targets thousands of kilometres away. Officials in Riyadh and the Saudi Embassy in Washington did not respond to requests for comment. Having such a programme could further strain relations with the United States, the kingdom's longtime security partner, at a time when ties already are being tested by the killing of Washington Post ...