"Congress has not authorized war with Iran".
"There are a lot of people in my shoes that are going to support standing up to Iran", he said, "but we need to understand what we're doing".
It was a telling remark from the supreme leader.
"We are very anxious about the risk of a conflict happening by accident with an escalation that is unintended", British Foreign Secretary Jeremy Hunt told reporters in Brussels.
European Union chief Federica Mogherini said on Monday that she does not want to see a military escalation between the USA and Iran.
The Trump administration ordered the withdrawal of all non-emergency personnel from the USA diplomatic mission to Iraq after the administration announced Iran or its proxies in the region were an escalating threat.
Last week, USA officials said they had detected signs of Iranian preparations for potential attacks on US forces and interests in the Middle East, but Washington has not publicly provided any evidence to back up claims of an increased Iranian threat.
The State Department has ordered all non-emergency U.S. government employees at the U.S. Embassy in Baghdad and the U.S. consulate in Erbil to leave the country, according to a statement posted on the embassy's website Wednesday.
Iraq has said it will keep strong ties with Iran, but also with the United States and regional neighbours, some of whom, like Saudi Arabia, consider Tehran an archrival.
A senior Iranian official said on Wednesday that any conflict in the region will have "unimaginable consequences".
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"The Trump administration has not provided any information to this committee on the intelligence behind their decisions, or what they plan to do in Iraq or Iran", said Senator Bob Menendez, the senior Democrat on the Senate Foreign Relations panel. The 2003 US-led invasion of Iraq took place without the backing of the United Nations and was later dubbed illegal by Secretary-General Kofi Annan.
Iran, for its part, has designated all U.S. troops stationed in the region as terrorists.
Last week, Iran notified non-U.S. signatories of the nuclear deal-China, France, Germany, Russia, and the UK-of its decision to halt some commitments under the nuclear deal.
It was unclear how many personnel were affected, and there was no word on any specific threat, but visa services were suspended at the heavily fortified United States missions.
Iran has thus faracted with restraintin the face of USA belligerence, urging diplomacy and attempting to restart negotiations with Europe over the terms of the Iran nuclear accord. But other than Netanyahu, these parties have kept quiet this week.
Saudi Arabian Minister of Energy Khalid al-Falih said that the latest attacks caused a fire, now contained, and minor damage at one pump station, but did not disrupt oil output or exports of crude and petroleum products.
Late Wednesday, Anwar Gargash, the UAE minister of foreign affairs, said the Saudi-led coalition would "retaliate hard" for attacks on civilian targets, without elaborating.
"This is an imminent threat to our personnel", said a second official.
"Abu Dhabi wants these actions", Karasik said of the tension with Iran, "and Saudi [Arabia] tags along".
The administration declined to specify what specifically prompted the staff withdrawal, but defense and security officials have warned in recent weeks there were "escalatory indications and warnings" and a "credible threat" posed by Iran.