(CNN) Hundreds of lawmakers in Germany, France and the UK wrote an open letter to the US Congress asking it to back the Iran nuclear deal, despite US President Donald Trump's threat to terminate the agreement next month.
"Abandoning the deal would diminish the value of any promises or threats made by our countries. It would also diminish our capability to keep Iran nuclear-free after the expiration of the special provisions of the JCPOA," the letter reads. "If we maintain our alliance now, we will be in the position to keep Iran's nuclear aspirations in check in the long run."
The letter continues: "But let us be clear: if the deal breaks down, it will well-nigh be impossible to assemble another grand coalition built around sanctions against Iran. We must preserve what took us a decade to achieve and has proven to be effective."
The 2015 agreement, known as the Joint Comprehensive Plan of Action (JCPOA ), was the crowning achievement of 20 months of grueling negotiations involving the US, France, Germany, Britain, Russia, China and Iran. It guarantees that Iran's nuclear program will remain peaceful, without developing nuclear weapons, in exchange for lifting US and EU nuclear-related sanctions that have crippled Iran's economy. The International Atomic Energy Agency was charged with verifying that Iran adheres to the agreement with regular inspections of Iranian nuclear facilities.
While the Obama administration had lauded the deal as a triumph of diplomacy, President Trump has dismissed it as a "major embarrassment" for the US. In January, he warned Britain, France and Germany that they must "fix the terrible flaws of the Iran nuclear deal" by May 12 or he would refuse to honor the sanctions relief promised in the agreement, threatening to terminate the JCPOA entirely.
Omid Nouripour of the Green Party in Germany signed the letter because he believes the deal keeps Iran in check.
"We know the deal with Iran is far from perfect: But no deal means no inspections. And if Iran gets the bomb, it triggers further proliferation across the Middle East," he told CNN. "This really just distracts from the other problems in Iran we are all concerned about: the terrible human rights situation in the country, Iran continuing to threaten Israel. So let's come together and put away these disputes over the JCPOA."
Versions of the open letter, which Nouripour said was signed by more than 400 lawmakers, were simultaneously released to the New York Times, Der Spiegel, Le Monde and the Guardian. The letter was timed to publish before the May deadline imposed by President Trump. It also adds pressure on the White House just days before it is set to welcome French President Emmanuel Macron and German Chancellor Angela Merkel next week.