In a letter to the United Nations (UN) Security Council, the three countries said they have "worked tirelessly to preserve the nuclear agreement and remain committed to do so," adding that any decision or action taken to reimpose sanctions against Iran would be "incapable of legal effect."
The UN sanctions relief for Iran was agreed to under a 2015 nuclear deal known as the Joint Comprehensive Plan of Action (JCPOA). Under the deal, Iran agreed to dismantle part of its nuclear program in exchange for relief from economic sanctions.
The Trump administration has insisted that international sanctions be reimposed on the Middle Eastern country in September, with US Secretary of State Mike Pompeo tweeting late last month that the "US will oppose" any resolution to continue sanctions relief.
In May 2018, the United States pulled out of the JCPOA and reimposed sanctions against Iran that had been lifted under the terms of the deal, as well as enacted new ones, after claiming that the deal allowed Iran to continue to enrich uranium. US President Donald Trump criticized the deal in 2018 while announcing the US' withdrawal from it, calling it "decaying and rotten" and "an embarrassment" to him "as a citizen."
"It is clear to me that we cannot prevent an Iranian nuclear bomb under the decaying and rotten structure of this deal," Trump said. "The Iran deal is defective to its core."