WASHINGTON — A group of Republican senators on Thursday warned European nations not to try to flout U.S. sanctions on Iran that will soon be re-imposed after President Donald Trump withdrew from a landmark nuclear accord.

The 10 senators, all of whom opposed the 2015 agreement, said in a letter to the ambassadors of Britain, France and Germany that they would be “particularly troubled” by any efforts to evade or undermine the sanctions. They said attempts to do so could be met by congressional action. A first set of U.S. sanctions lifted by the Obama administration under the terms of the nuclear deal is to be restored on Aug. 4. A second set will be re-imposed on Nov. 4.

The senators, including outspoken Iran deal critics Ted Cruz of Texas, Marco Rubio of Florida and Tom Cotton of Arkansas, noted that the sanctions are matters of U.S. law and had been eased only because the previous administration had approved of the deal, which Trump pulled out of in May.