Russia¡¯s war on Ukraine is reshuffling Middle East diplomacy and forcing the U.S. to reassess the political costs of reviving the 2015 nuclear accord with Iran.

Clinching the deal after a year of negotiations now hangs on a sticking point that people familiar with the talks say has emerged as the most politically explosive for the administration of U.S. President Joe Biden ¡ª whether to remove Iran¡¯s Islamic Revolutionary Guard Corps (IRGC) from the U.S. list of terrorist organizations.

The designation isn¡¯t directly linked to the original pact, which curbed Tehran¡¯s atomic activity in return for sanctions relief, but Iran has insisted all along that it be scrapped.