NEW YORK (Dispatches) -- Top diplomats from Germany, Russia, China and Italy insisted Thursday there can be no turning back on the Iran nuclear deal after President Donald Trump suggested that he may seek a renegotiation or simply walk away from the pact.
"How are we going to convince countries like North Korea that international agreements provide them with security - and in so doing make them commit to future disarmament efforts - if the only international example for such an endeavor being successful, the agreement with Iran, no longer has effect?" asked Germany's Vice Chancellor and Foreign Minister Sigmar Gabriel, addressing the UN General Assembly.
Italy's UN Ambassador Sebastiano Cardi said after a Security Council meeting that the escalating situation with North Korea should serve as a cautionary tale for not abandoning the Iran deal.
"When you see the DPRK (North Korea) proliferation issue … and then you have the kind of controlled agreement on Iran, that is the way to go."  
Russia's top diplomat, Foreign Minister Sergey Lavrov, in his address, called the Iran deal one of the "more important factors of regional and international security" today. Chinese Foreign Minister Wang Yi also reiterated support. No agreement is perfect, he said, but if the accord is discarded, the entire non-proliferation system would suffer, the Xinhua news agency reported.
The chorus of international support was countered by a succession of senior Trump aides who repeated the president's objections to the pact in television interviews on Thursday.
In his speech to the General Assembly on Tuesday, Trump called the accord "nothing short of an embarrassment" and the "worst one-sided deal perhaps in American history."  
Iran has ruled out any renegotiation of the agreement and has said that any abandonment of the deal would lead it to immediately resume enrichment of uranium.  
U.S. officials have said in recent weeks that Trump may try to supplement the deal by extending its provisions that ban Iran from possessing significant stockpiles of enriched uranium for 15 years.
U.S. National Security Adviser H.R. McMaster said Trump's decision on the deal would be part of a broader restructuring of U.S. policy toward Iran, which he said had focused entirely on negotiating and defending the nuclear agreement at the expense of other matters, including Iranian support for Lebanon's Hezbollah movement and for Syrian President Bashar Assad.
"Our approach to Iran has to change fundamentally," McMaster said on CBS.
U.S. Secretary of State Rex Tillerson on Wednesday had the highest-level encounter between the U.S. and Iran of Trump's presidency, meeting and shaking hands with Iranian Foreign Minister Muhammad Javad Zarif. The host of that meeting of parties to the agreement, EU foreign policy chief Federica Mogherini, said all sides agreed that the deal is working.
Tillerson, however, said that while Iran might be meeting its obligations to the letter of the deal, it is violating its spirit.