The group of 10 senators, who all opposed the 2015 accord, wrote an open letter to the ambassadors of Britain, France and Germany, which explained that the US would be “particularly troubled” by any efforts by its European allies to undermine the sanctions and warned that any such attempts could be met with congressional action.

The senators, including Ted Cruz (Texas), Marco Rubio (Florida) and Tom Cotton (Arkansas), said that these sanctions were enshrined in US law and had only been lifted because the previous administration approved of the deal, known as the Joint Comprehensive Plan of Action (JCPOA).

The letter read in part: “We write to urge you to comply with all American sanctions but also to emphasize we would find it particularly troubling if you sought to evade or undermine American statutes. These laws were passed by Congress, signed by President Obama and will be enforced by President Trump.”

It continued: “Any attempt to evade or subvert them could well prompt congressional action, in coordination with other elements of the U.S. government, to ensure their integrity.”

The US sanctions that were lifted under the deal by then-President Obama will begin rolling back on August 4, while the second set of sanctions will be re-imposed on November 4. The US has consistently warned its allies to end its trade with Iran by this deadline or they and their companies will be subject to US secondary sanctions and potentially even blocked from the US financial markets.

While Europe has struggled to keep the deal alive and vowed to protect its companies from US sanctions, many European businesses have already pulled out of Iran or have made plans to do so by the November deadline.

The US aims to cuts Iran’s oil exports, which constitute a great deal of their economy, to zero by November. In response, Iran repeatedly threated to close the Strait of Hormuz, when one-fifth of global oil exports, flow through and even threatened the US with the “mother of all wars”.

Trump responded on Sunday in an all-caps tweet, telling Iranian President Hassan Rouhani to never threaten the US ever again or else be prepared to face consequences the likes of which no country has ever faced before.