The US believes it knows who was behind the damaging drone attacks on two Saudi Arabian oil facilities and is "locked and loaded", Donald Trump has warned.
However, the president tweeted that American officials were "waiting to hear" from the Middle Eastern kingdom "as to who they believe was the cause of this attack, and under what terms we would proceed".
The attacks on the state-owned Saudi Aramco oil facilities in Abqaiq and Khurais, disrupted about half of the Saudi Arabia's oil capacity, or 5 per cent of the daily global oil supply.
Houthi rebels who are battling Saudi led forces in Yemen have claimed responsibility for the strikes.
Mr Trump tweeted there was "reason to believe that we know the culprit", without naming them.
However, Mike Pompeo, the US secretary of state, has pointed the finger at Iran, saying there was "no evidence" the drones came from Yemen.
Iran's foreign minister Javad Zarif denied his country was responsible, adding that "blaming Iran won't end the disaster" in Yemen.
Saudi Arabia oil supply was attacked. 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!
— Donald J. Trump (@realDonaldTrump)
Mr Trump's comments came shortly after he authorised the release of oil from the US Strategic Petroleum Reserve (SPR) if needed in a quantity to be determined because of
He said the amount released would be what was "determined sufficient to keep the markets well-supplied".
He added: "I have also informed all appropriate agencies to expedite approvals of the oil pipelines currently in the permitting process in Texas and various other States."
In a later tweet he added: "Plenty of oil."
The US president also appeared to play down the chances that he might be willing to meet with Iranian officials, saying reports that he would do so without conditions were not accurate.
"The Fake News is saying that I am willing to meet with Iran, 'No Conditions.' That is an incorrect statement (as usual!)," Mr Trump wrote on Twitter.
His comments appeared to contradict Mr Pompeo's comments last week, who said the president was "prepared to meet with no preconditions."