But saying so doesn't make it so.
Graham said it was "clear" that such a sophisticated attack - drones firing missiles into the world's largest processing plant and an oilfield in Saudi Arabia - could only have originated with direction and involvement from the "evil regime in Iran".
The unequivocal statement came a day after Trump said he was unwilling to meet under a scenario with 'no conditions'. Often, top-level diplomacy between adversaries only proceeds after both sides agree to take a few steps to ease tensions.
The aides were echoing Trump's own words.
Trump told reporters on Tuesday that he believes Iran is not yet ready for talks with the US but will be.
Other Republicans senators including Marco Rubio and Ron Johnson said they fully believe Iran was responsible for the Saudi strike. Asked on NBC's "Meet the Press" in June whether he'd set any conditions for meeting Iranian leadership, Trump replied: "Not as far as I'm concerned".
"Stopping all sanctions is an indispensable precondition for constructive diplomacy".
Iran's Ministry of Foreign Affairs on Sunday called the USA allegations "meaningless" and said they were meant to justify actions against Iran.
"The President of the United States displays nonsense; however, this should not lead us to ignore the mischief of the USA regime", Khamenei told a group of students, before taking to Twitter to expand his range of insults further. And it's absolutely working.
However, the United States has said it will remain open for talks with Iran.
Q: "So, Secretary Pompeo, for clarity on this, can you foresee a meeting between President Trump and the Iranian leader later this month surrounding the United Nations?".
Secretary of State Mike Pompeo at a press conference on Tuesday said Trump was willing to meet with Rohani without preconditions.