The US secretary of state Mike Pompeo’s bald claim this weekend that Iran was responsible for the attack on the Saudi oilfields came with no marshalled public evidence, but dampens any likelihood that Donald Trump will countenance a meeting with Tehran in the near future or press ahead with tentative peace talks with Houthi rebels in Oman.

Lindsey Graham, one of Trump’s foreign policy supporters in the Senate, was clear talks with Iran are now off the agenda saying: “The Iranian regime is not interested in peace – they’re pursuing nuclear weapons and regional dominance.”

For the moment Europe is not attributing blame. Britain in its statement condemning the attack did not explicitly blame Iran, but called on the Houthis to desist.

Play Video 0:52 Saudi Arabia: major fire at world's largest oil refinery after attack – video

The Houthis, eager to claim such a devastating strike in the heart of the Saudi oil empire, insist that the drone was fired by its forces, one of dozens of attacks mounted by the Houthis of varying sophistication in the last year, and was prepared and executed internally by its forces without any help from Tehran.

The only help came from intelligence given to the Houthis from inside Saudi Arabia, the Houthis said. Iran for its part predictably rejected Pompeo’s claims, describing them as lies and deceit.

But the US state department, in seeking to defend the four-year Saudi assault on Houthis in Yemen, has increasingly portrayed the Houthis as a tame creature of Iran, dependent on Tehran for intelligence, technology transfer and targeting advice. An article in the Wall Street Journal by Brian Hook, the US special representative for Iran, last week claimed Iran was trying to turn Yemen into another Lebanon, a country in which militia in tune with Tehran are given carte blanche.

The truth may be more subtle. An attack in May on a Saudi oil-pumping station, which Saudi officials initially blamed on the Houthis and Iran, later emerged to have been launched by an Iranian-backed militia in Iraq, according to US officials. It is possible the US is implying the same Iranian groups were responsible for this latest assault, something Iraq naturally denies. Kuwaiti claims that drones were seen over its airspace would add credence to the suggestion that drones were fired from Iraqi territory.

Either way the assault serves to highlight US claims that any future peace agreement with Iran will have to include measures to rein in the Iranian-backed militia that operate in Syria, Yemen, Lebanon and Iraq. It is a tall order since each of these militia do not regard themselves simple cyphers for Iran.

The assault also raises fresh questions about Saudi vulnerability to drone assaults on its civilian and military infrastructure. There have been dozens of attacks at Saudi airports, a desalination plant and oil infrastructure. Suspected Houthi missiles, mainly the UAV-X originating from the Yemeni border, are launched at Saudi Arabia, sometimes several times a week. Most are intercepted, but it only takes one or two to get through for the impact to be devastating.

The UN in its reports has not been definitive that the drone technology has been prepared by the Iranians, but it certainly implies Iran could do more to prevent gaining access to the technology.

The assaults also highlight the division in the anti-Houthi coalition between Saudi and United Arab Emirates. The UAE announced two months ago it was pulling back from the four-year war claiming its goals had been secured. Since then a UAE-backed secessionist movement, the Southern Transitional Council, has seized power in Aden, leaving Saudi’s sponsor Abdrabbuh Mansur Hadi further from reclaiming control.

The coming weeks will determine whether the Saudis will reckon the intractable Yemen war is worth pursuing, despite the ever increasing threat to the Saudi oil industry, its lifeblood and saviour.