US Secretary of States Rex Tillerson declared on Wednesday that Iran must withdraw its forces and militias from Syria. He also expressed concern over Saturdays confrontation between Israel and "Iranian assets" in Syria. Syrian air defenses shot down an Israeli F-16 jet on Saturday after it bombed a site used by Iran-backed position in Syria. Tillerson made his remarks during a joint press conference with Jordanian Foreign Minister Ayman al-Safadi in Amman. Iran quickly responded to the US official, with Ali Akbar Velayati, top aide to Irans Supreme Leader, saying that “Iran’s military presence in Syria was based on invitation” of the Syrian regime. "Those should leave Syria who are there without the permission” of the regime, Velayati was quoted as saying by ISNA. Addressing the peace process in the Middle East, Tillerson said that the US administrations work on a new Middle East peace plan is "fairly well advanced” and President Donald Trump will decide when to announce it. Tillerson also signed a five-year aid package that extends US support to Jordan, a key regional ally, despite Trumps threat to withhold support from states opposed to his decision to recognize Jerusalem as the capital of Israel. Commenting on the peace plan, Tillerson said: "I have seen the plan... It’s been under development for a number of months. I have consulted with them on the plan, identified areas that we feel need further work. "So I think it will be up to the president to decide when he feels it’s time and he’s ready to put that plan forward. I will say it’s fairly well advanced…" In December, Trump reversed decades of US policy in December to recognize Jerusalem as Israel’s capital and set in motion the process of moving the US embassy from Tel Aviv. The move triggered outrage in the Arab and Muslim world, and led Palestinian President Mahmoud Abbas to declare that he would not cooperate with the United States as a mediator. Trump has threatened to cut off financial aid to countries that backed a UN resolution calling for Washington to reverse its Jerusalem decision. Jordan backed the resolution. King Abdullah’s Hashemite dynasty is the custodian of the Muslim holy sites in Jerusalem, making Amman particularly sensitive to any changes of status there. Tillerson and Safadi signed the non-binding memorandum of understanding (MoU) for $6.375 billion in aid starting this year. The previous such MoU between Jordan and the United States was for three years. "This MoU commitment highlights the pivotal role Jordan plays in helping foster and safeguard regional stability and supports US objectives such as the global campaign to defeat ISIS, counter-terrorism cooperation, and economic development," the US State Department said in a statement. Tillerson also met in Amman with a delegation from the Syrian High Negotiations Committee (HNC) headed by Nasr al-Hariri. Hariri tweeted after the closed-door talks that the HNC had held an “important meeting” with the US official, adding that the delegation had stressed the need try war criminals and hold the regime accountable for chemical weapons attacks. It also underlined the need to commit to the Geneva peace talks and “de-escalation” zones agreements.