Iran threatened on Sunday to withdraw from the nuclear Non-Proliferation Treaty (NPT) in response to the United States tightening sanctions on Tehran. Iran’s “choices are numerous, and the country’s authorities are considering them ... and leaving NPT is one of them,” state broadcaster IRIB’s website quoted Foreign Minister Mohammad Javad Zarif as saying. Tensions between Tehran and Washington have risen since the Trump administration withdrew last year from a 2015 international nuclear deal with Iran and began ratcheting up sanctions. Earlier this month, the United States blacklisted Iran’s Revolutionary Guards (IRGC) and demanded buyers of Iranian oil stop purchases by May or face sanctions. Iran has threatened in the past to leave the NPT, as US President Donald Trump moved to scrap the 2015 deal with world powers - the United States, Russia, China, Germany, Britain and France. On Wednesday, Zarif called the IRGC blacklisting “absurd”, but suggested Iran did not plan to respond militarily unless the United States changed the rules of engagement guiding how it interacts with Iran’s forces. The US military has not suggested it would alter its behavior after the blacklisting.