US policy towards Iran has taken a drastic turn. When former president Barack Obama was in office, Iran was free to act how it pleased and it was safe in the knowledge that the US administration would not say anything.

Obama was so keen to leave the Iran nuclear deal as his legacy that he granted Iran concession after concession and led a policy of appeasement.

Even before being elected, Trump spoke about Obama’s failed policy and said that he would approach the situation differently if took office. He did get elected and he did change the direction of foreign policy. He has warned Iran about its behaviour on many occasions and is following through on the threats he makes.

Over the weekend, the Trump administration sent a warning to Qassem Soleimani – the commander of the country’s Islamic Revolutionary Guard Corps (IRGC). It also reaffirmed that it was going to take action to curb Iran’s use of proxy groups across the whole region.

Mike Pompeo, the director of the CIA, said that he wrote to Qassem Soleimani, the head of the Quds Force – the IRGC’s foreign operations arm. He said that this action was prompted by Soleimani’s indication that forces he controls could go after US interests in Iraq.

Pompeo said that the letter was a warning to Soleimani that the United States would hold him and his country accountable “for any attacks on American interests in Iraq by forces that are under their control”. He added: “We wanted to make sure he and the leadership in Iran understood that in a way that was crystal clear.”

The Iranian media reported that a senior official of the Iranian regime said that Soleimani refused to take the letter because he has nothing to say to the US administration.

National security adviser HR McMaster said that Iran is fuelling and accelerating the violence that already exists across the Middle East and explained that it is doing so because it wants to “take advantage of chaos and weak states to make them dependent on Iran for support”.

Speaking about the failed policy of appeasement and the badly-negotiated nuclear deal, McMaster said: “In recent years, what we can say in retrospect, it was unrealistically hopeful [US] strategy that, given the nuclear deal – that this president called worst deal ever – that this deal will result in an Iran that would integrate effectively in region. The exact opposite happened. The fact that we were trying to accommodate Iran has empowered Iran across the globe, and when president says he inherited a mess that is in greater Middle East, we have to address growing Iranian capability, and their use of militias, proxies and terrorist organisation.”