President Donald Trump has penned a letter to Iran’s Supreme Leader Ali Khamenei, calling on Iran to renegotiate the nuclear agreement. The historic Iran nuclear agreement, or the Joint Comprehensive Plan of Action (JCPOA), was signed in 2015 by Iran, the United States, five permanent members of the UN Security Council, Germany, and the European Union. The deal granted sanctions relief to Iran in return for enforced restrictions on its nuclear program, such as the restriction of uranium enrichment and adherence to international inspections. Despite that, Trump solely pulled the U.S. out of the deal in 2018, calling it \”one of the worst and most one-sided transactions\” that America had entered into. The withdrawal caused fierce global backlash, with European nations trying to enforce the deal. The potential for resurrecting the nuclear accord remains uncertain, but Trump’s letter is an important change of approach, revealing a willingness to engage diplomatically in the face of rising regional tensions, writes Peter Bergen. He says if returned, the letter could have several purposes: lessening Iran’s nuclear threat, softening U.K. policy concessions to Israel, and bolstering Trump’s diplomatic credibility.