US president cautions Iran against reprisal for Soleimani killing, saying targets will be hit 'very fast and very hard,' as tensions soar amid fears of all-out war

Organizers say demonstrations held in some 70 US cities as prospects of major conflagration grow in wake of killing of top Iranian general

Officials tell CNN there are intense efforts to assess when Tehran will attempt to retaliate for killing of top general -- with estimates ranging between days and weeks

PM and US secretary of state talk by phone for third time this week, with the latter hailing 'Israel's steadfast support in defeating terrorism'

Spokesman for agency says it will boost visibility and vigilance at various sites amid Iranian theats; Arlington Cemetery also upping security measures

No reports of casualties; Washington is bracing for Iranian retaliation after Tehran vowed to avenge death of Qassem Soleimani; top Iraqi paramilitary chief also killed in strike

IRGC commander also warns of the importance of shipping channels in region, says Tehran has identified vital American targets

'We have to act and we will act,' envoy tells CNN; Hezbollah political official says Washington 'made a mistake' and will soon come to regret hit on Iranian general

Foreign minister and top military commander say Washington 'resorted to diplomatic measures,' with Javid saying request passed via Switzerland

Tehran's nuclear activities and tanker attacks, as well as targeting of Saudi oil facility and US drone, along with Trump's pullout from nuke deal, all contributed to situation