United States President Donald Trump says his country is "locked and loaded" to respond to attacks which inflicted serious damage on Saudi Arabia's oil infrastructure over the weekend.
It is the first time the US President has hinted at a potential American military response to the drone attacks, which slashed Saudi oil production by half and led both the kingdom and the United States to announce they may tap their strategic reserves.
"There is reason to believe that we know the culprit, are locked and loaded depending on verification, but are waiting to hear from the Kingdom as to who they believe was the cause of this attack, and under what terms we would proceed!" Trump tweeted.
Houthi rebels in Yemen, where a Saudi-led coalition is bogged down in a five-year war, claimed responsibility for Saturday's strikes, which targeted two plants owned by state energy giant Aramco.
But US Secretary of State Mike Pompeo pointed the finger squarely at Tehran, saying there was no evidence the "unprecedented attack on the world's energy supply" was launched from Yemen.
"The United States will work with our partners and allies to ensure that energy markets remain well supplied and Iran is held accountable for its aggression," Pompeo said.
The US accusations triggered angry retorts from Iran, which said they were designed to act as a pretext for future hostile actions against the Islamic Republic.
"Such fruitless and blind accusations and remarks are incomprehensible and meaningless," foreign ministry spokesperson Abbas Mousavi said.
Tehran and Washington have been at loggerheads since May last year, when Mr Trump pulled the US out of a landmark 2015 deal with world powers that promised Iran relief from sanctions in return for curbs on its nuclear program.
