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

Officials say 'significant cache' of weapons, which contravene UN Security Council resolutions on Yemen conflict, showcase Tehran's backing of Houthi rebels in the country

Tehran's hybrid war strategy has secured it an advantage over US and allies in region, who have no effective response, according to major report by UK think tank

International Crisis Group says Saudi Arabia doesn't know how to extract itself from war against Houthi rebels, needs US guidance