Senior US Democrats led the outcry on Friday against Donald Trump’s dramatic almost-launch of military action on Iran and the last-minute pullback – calling the crisis “self-inflicted” by America and pressing for a swift de-escalation.

They also demanded oversight from Congress on decisions involving any eventual strikes.

Trump says he stopped airstrike on Iran because 150 would have died Read more

Elizabeth Warren, the senator from Massachusetts who is gaining traction in the race for the 2020 Democratic presidential nomination, accused the president of instigating “another unnecessary conflict”. She said: “There is no justification for further escalating this crisis – we need to step back from the brink of war.”

Joe Biden, the current frontrunner in the Democratic contest for the 2020 election, had a personal take on the crisis as one half of the previous Obama-Biden administration, which in 2015 secured a nuclear deal with Iran. He lamented that by tearing up that agreement last year, Trump had only succeeded in making Tehran more aggressive in what he called a “self-inflicted disaster”.

In a Twitter stream posted a few hours before Trump’s decision to turn back from military strikes, Biden added that “by walking away from diplomacy, Trump has made military conflict more likely. Another war in the Middle East is the last thing we need.”

Play Video 1:35 Trump says he stopped airstrike on Iran in latest escalation of tensions – video report

Bernie Sanders, another leading contender for the Democratic nomination for the White House, was one of several to point out the authority vested in Congress to declare war – a power that has become heavily eroded since the 9/11 terrorist attacks on the US. “Congress must assert its constitutional authority and stop Trump from going to war,” he said.

While most Democrats were focused on the risk of war, some decried the almost haphazard manner in which Trump had called off airstrikes with just minutes to spare. Trump said he made the decision after he was informed that the strikes could cause the loss of up to 150 Iranian lives – but in that case, Democrats wanted to know, why was he informed so late in the process?

Anthony Brown, the Democratic vice-chairman of the House armed services committee, told CNN: “But 10 minutes before a potential strike against Iran – that demonstrates a broken system, a lack of understanding and knowledge by our commander-in-chief.”