The Trump administration has said it was “officially putting Iran on notice” in reaction to an Iranian missile test and an attack on a Saudi warship by Iranian-backed Houthi rebels in Yemen but gave no details about how Washington intended to respond.

The threat was made on Wednesday by the national security adviser, Michael Flynn, in his first public statement since taking office.

Speaking in the White House briefing room, Flynn said a missile launch on Sunday and a Houthi attack on a Saudi frigate on Monday underlined Iran’s “destabilizing behavior across the Middle East.”.

Flynn did not specify how the new administration would respond. Asked for clarification, the White House spokesman, Sean Spicer, said the president wanted to make sure the Iranians “understood we are not going to sit by and not act on their actions”.

At a White House briefing, senior administration officials repeatedly refused to rule out any options for a US response, including military intervention.

“There are a large number of options available to the administration,” one senior official said. “We’re going to take appropriate action.”

Asked if measures under consideration included a military option, the official replied: “We are considering a whole range of options.”

The official declined to say whether the White House had sent a message to Tehran putting it on notice.

“We are in the second week. We do not want to be premature or rash or take any action that would foreclose options or unnecessarily contribute to a negative response.”

The announcement was not accompanied by any change in the US military stance in the region, nor any immediate additional deployments.

“We saw the statement as well,” said a spokesman for US central command, which runs operations in the Middle East. “This is still at the policy level, and we are waiting for something to come down the line. We have not been asked to change anything operationally in the region.”

The Pentagon was informed before the announcement and the defense secretary, James Mattis, prevailed upon Flynn to soften his language about Iran from an earlier version. At the time of the Flynn’s statement, Mattis was en route to Asia for an official visit to Japan and South Korea.

Ali Vaez, an Iran expert at the International Crisis Group in Washington, said: “It’s either an empty threat or a clear statement of intent to go to war with Iran. Both are reckless and dangerous … In an attempt to look strong, the administration could stumble into a war that would make the Afghan and Iraqi conflicts look like a walk in the park.”

Iran reacted defiantly on Thursday, saying it would continue its “self-defence activities”. Ali Akbar Velayati, the senior foreign policy adviser to the country’s supreme leader, Ayatollah Ali Khameni, said Tehran would not seek permission from any country to defend itself.

“It is not the first time that an inexperienced person in the US has threatened us,” he said, referring to Trump during a meeting in Tehran.

“Trump would realise over the time that such hollow bragging would only discredit him in the eyes of the general public,” Velayi added. “The US was defeated even in countries less powerful than us.”

Iran’s president, Hassan Rouhani, called Trump a political novice and said it “will cost the US a lot” while it waits for its president to “learn what is happening in the world”.

During the election campaign, the Trump team repeatedly signaled that it would take a much tougher line towards Tehran. Both Flynn and Mattis have long portrayed Iran as a serious strategic threat to US interests.

Earlier on Wednesday, the Pentagon confirmed that Mattis had spoken by phone to his Saudi counterpart, Prince Mohammed bin Salman.

According to the defense department account, the conversation “reaffirmed the importance of the US-Saudi Arabia strategic relationship, particularly to countering new and emerging security challenges in the Middle East”.

According to the Saudi version, the discussion was more pointedly aimed at Iran, and both men expressed “their full rejection of the suspicious activities and interventions by the Iranian regime and its agents”.

Flynn used his appearance at the daily White House press briefing to criticize the Obama administration, which he claimed had “failed to respond adequately to Tehran’s malign actions – including weapons transfers, support for terrorism, and other violations of international norms”.

He noted that Donald Trump had “severely criticized the various agreements” the previous administration and the UN made with Iran as being “weak and ineffective”. It was an apparent reference to the nuclear deal the US and five other major powers made in July 2015, which was formalized in a UN security council resolution, under which Iran drastically reduced its nuclear program in return for sanctions relief.

The UN resolution endorsing the deal did not impose a complete prohibition on Iranian missile tests, but called on Tehran “not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons, including launches using such ballistic missile technology”.

Earlier on Wednesday, Iran confirmed it had tested carried out a missile test on Sunday. Defence minister Hossein Dehghan did not describe the weapon, but insisted that the test was within its rights “The recent test was in line with our plans and we will not allow foreigners to interfere in our defence affairs,” he told Tasnim news agency. “The test did not violate the nuclear deal or [UN] Resolution 2231.”

Flynn said: “Instead of being thankful to the United States for these agreements, Iran is now feeling emboldened … As of today, we are officially putting Iran on notice.”

During his tenure as the head of the Defense Intelligence Agency (DIA), Flynn was reported by the New York Times to have told his subordinates he had concluded that Iran was behind the 2012 terrorist attack on the US diplomatic compound in Benghazi in Libya, and ordered them to find evidence to prove it.

The DIA found no evidence of any Iranian connection to the attack, which was carried out by a Sunni extremist group, Ansar al-Sharia.

Iran is a Shia-run state, which sees Sunni militancy as a serious threat.

The civil war in Yemen pits a Saudi-led coalition backing President Abed Rabbo Mansour Hadi against supporters of the previous president Ali Abdullah Saleh, and ethnic Houthi forces, who receive some backing from Iran, but are not generally thought to be completely under Tehran’s control.

About 10,000 people have been killed and both sides have been accused of war crimes, but Saudi-led air strikes have been blamed by human rights groups for the bulk of civilians casualties, as they have hit hospitals, schools and other non-military targets. The coalition is also enforcing a naval blockade of rebel-held areas.

In its last weeks, the Obama administration began limiting arms sales to Saudi Arabia out of concern over civilian casualties.

The threat, along with the administration’s refugee ban, represent major departures from previous US foreign policy, and came from the White House before the administration’s designated secretary of state, Rex Tillerson, had been confirmed.

Tillerson was confirmed in the Senate just over an hour after Flynn’s threat but he will inherit a state department in turmoil, with a growing wave of internal resistance against the executive order suspending arrivals from seven predominantly Muslim countries. The state department has also been the main institutional backer of the Iran nuclear deal.

Source: / theguardian/