The strikes, which destroyed half of the kingdom’s oil production capacity, were claimed by Iran-backed Houthi rebels in Yemen.
On Sunday night Mr Trump said the US was “locked and loaded” and believed it knew who was truly behind the attack.
But Bernie Sanders, who is gunning for the Democratic nomination for president, tweeted: “Mr. Trump, the Constitution of the United States is perfectly clear. Only Congress—not the president—can declare war.
“And Congress will not give you the authority to start another disastrous war in the Middle East just because the brutal Saudi dictatorship told you to.”
It came hours before Mr Trump was due to hold a rally in New Mexico, a state he lost in 2016 but hopes to flip in the 2020 election.
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