THE rule-by-tweeting Presidency of Donald Trump gained a menacing edge yesterday when he used social media to threaten Iran over its development of ballistic missiles.

Trump tweeted: “Iran has been formally PUT ON NOTICE for firing a ballistic missile. Should have been thankful for the terrible deal the US made with them!”

The Islamic Republic of Iran hit back, with Ali Akbar Velayati, senior adviser to Supreme Leader Ayatollah Ali Khamenei, saying: “This is not the first time an inexperienced person has threatened Iran.

“Iran does not need permission from any country to defend itself. The American government will understand threatening Iran is useless.”

Bahram Ghasemi, the Iranian foreign ministry spokesman, was also quoted by state news agency IRNA as saying the USA’s claims were “baseless, repetitive and provocative”.

Relations between the USA and Iran had already plummeted after President Trump signed his executive order banning Iranians and people from six other mainly Muslim countries from travelling to the USA.

Trump’s tweet that provoked the Iranian response echoed the comments from his national security adviser Michael Flynn.

Flynn said on Wednesday that the US will act against Iran unless it stops testing ballistic missiles, though neither Flynn nor the President would elaborate on what retaliatory actions the US would pursue.

Trump then tweeted yesterday: “Iran was on its last legs and ready to collapse until the US came along and gave it a life-line in the form of the Iran Deal: $150 billion.”

The deal mentioned by Trump was negotiated by the United Nations, the USA, the UK and other countries to try to prevent Iran developing nuclear weapons by putting money into the country’s infrastructure.

Trump has railed against the deal over many months but has not said if he will cancel the American part of it.

United Nations resolutions currently do not prohibit Tehran from conducting such missile tests but one states: “Iran is called upon not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons.”

Though Iran had at first denied testing a ballistic missile, the Government of Glasgow-educated President Hassan Rouhani confirmed that a missile had been tested for “defensive” purposes.

As a result, senior Trump administration officials said yesterday they were actively considering a “range of options” including economic measures and increased support for Iran’s regional adversaries.

Trump also too to Twitter after a row with Australia MP Malcolm Turnbull over an Obama deal to resettle 1,250 refugees in the US.

He tweeted that he would “study this dumb deal”.