American National Security Adviser John Bolton has said in Jerusalem that a US strike against Iran could happen at any time, despite Donald Trump’s last-minute decision on Thursday to call off retaliation for Iran’s shooting down of an American drone.

Mr Bolton said that President Trump’s decision should not be misinterpreted as a sign of weakness. Iran’s continued actions against the US and its Middle East allies did not suggest peaceful intentions and it should never be allowed to obtain nuclear weapons.

He had talks with Israeli Prime Minister Benjamin Netanyahu on Sunday ahead of a tripartite summit also involving Russia. The original focus had been Syria, but it is now likely to switch to Iran.

Mr Bolton tweeted afterwards: “Great meetings today with Israeli PM and NSA [National Security Adviser] Meir Ben-Shabbat. We re-affirmed our shared priority of confronting Iranian aggression throughout the region by continuing maximum economic pressure and increasing the cost of Iran’s malign activity.”

In  his remarks, Mr Netanyahu said that anyone believing “Iran's aggression commenced just now is living in a different dimension. We have been countering Iran's attempt to establish itself in Syria and assist Hezbollah."

Meanwhile, Foreign Office Minister Andrew Murrison is in Tehran, where he is calling for“urgent de-escalation" of regional tensions during talks with the Iranian government. The Foreign Office said he would be criticising Iran’s "regional conduct".