In 2015, to end 2 decades of sanctions on Iran in nuclear weapon, Barack Obama's administration along with 6 other countries formed an agreement called Joint Comprehensive Plan Of Action(JCPOA) Apart from Iran and Us the other countries in the agreement are China, France, Britain, Germany and Russia. And with this JCPOA a nuclear deal was signed between Iran and these 6 countries.
the features of the deal are:-
Iran should reduce its stock of enriched uranium by 975 and banned them from using it as a fuel for bomb.
Reduced the number of uranium centrifuges to 5000 and Iran can use only outdated and old centrifuges only.
Stopped Iran from operating Arak facility using Plutonium to make bomb.
Iran should permit IAEA inspections to verify Iran is not cheating with this nuclear deal.
But in May 2018 US President Mr. Donald Trump withdraw US from the JCPOA and nuclear deal with Iran. Instead he instate all the sanctions on Iran withdrawn in 2016violating the international nuclear agreement and UN resolution, breaking with its European allies. And he also stated that any nation who helps Iran in developing nuclear weapon will also face heavy sanctions from US.
But Iran said that it is happy that US left the deal. Iran's president Hassan Rouhani said he believed that the nuclear agreement could still survive, if other partners defy Trump. As he said other members in JCPOA were not happy about Trump's decision of withdrawal. This sanctions will definitely affect other countries who are doing business with Iran.
European Union countries were tried their best to influence Trump on staying with the nuclear deal. But instead of standing with European allies trump listened to middle east countries like Israel, Saudi Arabia and UAE. After nearly 7 months Iran the nuclear deal is still on. So what we can do is to wait and see whether Iran will make nuclear weapons or stick to the nuclear deal with the members of JCPOA and UN council.