American and Saudi officials are discussing terms of a mutual defence treaty that would resemble the robust military pacts that the US has with its close allies Japan and South Korea, a central component in President Biden’s high-stakes diplomacy to get Saudi Arabia to normalise relations with Israel, according to US officials. Under such an agreement, the US and Saudi Arabia would generally pledge to provide military support if the other country is attacked in the region or on Saudi territory. The discussions to model the terms after...