Russia has sharply criticised the US push for modifying the nuclear agreement with Iran, calling Washington’s demands "deplorable".
Russian foreign minister Sergey Lavrov warned that Moscow will not support the US demand for changes in the 2015 nuclear deal with world powers which saw Iran accept curbs on its nuclear programme in exchange for lifting international sanctions.
President Donald Trump kept the accord alive on Friday by extending sanctions waivers, but warned that the US would pull out of the deal in a few months unless its "terrible flaws" are fixed.
Mr Lavrov called the new US demands on Iran "deplorable", saying they raise doubts about Washington’s ability to observe international agreements.
He noted that the dismantling of the Iran nuclear deal would discourage North Korea from negotiating any future agreement to abandon its nuclear and missile programmes.
Mr Lavrov said: "We will not support what the US is trying to do - to change the text of the agreement to include things which are absolutely unacceptable for Iran."
Mr Trump said he would work with European allies to remove so-called sunset clauses that allow Iran to gradually resume advanced nuclear activities in the next decade.
He paired Friday’s concession with other, targeted sanctions on Iran for human rights abuses and ballistic missile development.
Iran warned that it will not accept any changes to the nuclear deal. The Europeans have indicated they are willing to discuss the matter with Washington, but have shown little enthusiasm over Mr Trump’s hard line.
Germany has said it will seek more detail on what the US wants and will analyse the situation with its European partners.
German Chancellor Angela Merkel’s spokesman, Steffen Seibert, stressed that Berlin stands by the nuclear deal.
Foreign ministry spokeswoman Maria Adebahr said officials would sit down with the Americans and "see what goal and request exactly Mr Trump’s comments contain".
She said Mr Trump’s statement appeared to have been directed "first and foremost to his own Congress".
The 2015 nuclear pact with Iran involved the US, the UK, France, Germany, China and Russia.