Investigators still trying to determine if Tehran behind attacks on Saudi oil; Lawmaker urges president to go to Congress as strikes could lead to 'a medium to large-scale war'

US president facing competing urges of keeping up pressure on Tehran to negotiate while deterring any further Iranian attacks and avoiding another Middle East war

In Australia, Esper and Pompeo suggest nations are quietly expressing support for plan; counterparts in Melbourne won't commit

Chairman of the US Joint Chiefs of Staff says he hopes other nations will soon sign up to join effort to protect commercial traffic in Persian Gulf area