The telling words that Starmer could - and couldn't - say about US strikes on Iran

When I got to Chequers on Sunday, the prime minister had clearly been up for most of the night and hitting the phones all morning with calls to fellow leaders in Europe and the Middle East, as he and others scrambled to try to contain a very dangerous situation.  His primary message was to try to reassure the public that the UK government was working to stabilise the region as best it could and press for a return to diplomacy.

But what struck me in our short interview was not what he did say but what he didn't - what he couldn't - say about the US strikes. It was clear from his swerve on the question of whether the UK supported the strikes that the prime minister neither wanted to endorse US strikes nor overtly criticise President Donald Trump.

Follow latest: Trump hails 'bullseye' strikes on Iran Instead, his was a form of words - repeated later in a joint statement of the E3 (the UK, Germany and France) - to acknowledge the US strikes and reiterate where they can agree: the need to prevent Iran having a nuclear weapon. He also didn't want to engage in the very obvious observation that President Trump simply isn't listening to Sir Keir Starmer or other allies, who had been very publicly pressing for de-escalation all week, from the G7 summit in Canada to this weekend as European countries convened talks in Geneva with Iran.

It was only five days ago that the prime minister told me he didn't think a US attack was imminent, when I asked him what was going on following President Trump's abrupt decision to quit the G7 early and convene his security council at the White House. When I asked him if he felt foolish or frustrated that Trump had done that and didn't seem to be listening, he told me it was a "fast moving situation" with a "huge amount of discussions in the days since the G7" and said he was intensely pressing his consistent position of de-escalation.

What else really could he say? He has calculated that criticising Trump goes against UK interests and has no other option but to press for a diplomatic solution and work with other leaders to achieve that aim. Before these strikes, Tehran was clear it would not enter negotiations until Israel stopped firing missiles into Iran - something Israel is still saying it is not prepared to do.

The US has been briefing that one of the reasons it took action was because it did not think the Iranians were taking the talks convened by the Europeans in Geneva seriously enough. It is hard now to see how these strikes will not serve but to deepen the conflict in the Middle East and the mood in government is bleak.

Iran will probably conclude that continuing to strike only Israel in light of the US attacks - the first airstrikes ever by the US on Iran - is a response that will make the regime seem weak. Read more:Iran may not have lost its ability to make a nuclear bombAnalysis: Iran may decide killing Americans is best way to retaliate But escalation could draw the UK into a wider conflict it does not want.

If Iran struck US assets, it could trigger Article 5 of NATO (an attack on one is an attack on all) and draw the UK into military action. If Iran chose to attack the US via proxies, then UK bases and assets could be under threat.

The prime minister was at pains to stress on Sunday that the UK had not been involved in these strikes. ???? Click here to listen to Electoral Dysfunction on your podcast app ???? Meanwhile, the UK-controlled airbase on Diego Garcia was not used to launch the US attacks.

There was no request to use the Diego Garcia base, the president moving unilaterally, underlining his disinterest in what the UK has to say. The world is waiting nervously to see how Iran might respond, as the PM moves more military assets to the region while simultaneously hitting the phones.

The prime minister may be deeply opposed to this war, but stopping it is not in his gift..