The US will move additional warships and fighter jets to the Middle East to help defend Israel from possible attacks by Iran and its proxies, the Pentagon has said.

It comes after Iran’s Supreme leader ordered a “direct attack” on Israel following the assassination of Hamas chief Ismail Haniyeh in Tehran. 

His death came just hours after Israel claimed it killed Fuad Shukr, the military commander of Iran's terrorist proxy in Lebanon, Hezbollah.

Gen Erik Kurilla, commander of US Central Command (CENTCOM), arrived in the Middle East on Saturday.

The trip by the general in charge of American forces in the region was already planned. However, in light of Tehran's pledge to retaliate, his visit will focus on building a multilateral defensive alliance similar to the one that fended off the vast majority of the more than 300 missiles and explosive drones Iran fired at the Jewish state in mid-April.

Hezbollah has separately vowed revenge for the targeted killing Shukr in Beirut on July 30.

Kurilla is expected to visit several Gulf states, Jordan and Israel. Amman is an important stop because King Abdullah II played a pivotal role during the April 13 onslaught in making interceptions from Iran and allowing the use of its airspace by US and Israeli jets to shoot down Iranian drones.

Jordan's Foreign Minister Ayman al-Safadi will visit Tehran on Sunday to discuss the security escalation in the Middle East following the Haniyeh assassination, the Qatari newspaper Al-Arabi Al-Jadid reported.

Meanwhile, the Pentagon said on Friday that the U.S. is boosting its defence posture in the Middle East in preparation for an expected attack against Israel by Iran and its terror proxies in Lebanon, Syria, Iraq and Yemen.

Defence Secretary Lloyd Austin "has ordered adjustments to U.S. military posture designed to improve U.S. force protection, to increase support for the defence of Israel, and to ensure the United States is prepared to respond to various contingencies," the Pentagon statement from deputy press secretary Sabrina Singh said.

Austin ordered the USS Abraham Lincoln carrier strike group to replace the USS Theodore Roosevelt carrier strike group. In addition, destroyers and cruisers capable of ballistic missile defence will be sent to the Eastern Mediterranean and Middle East.

"The secretary has also ordered the deployment of an additional fighter squadron to the Middle East, reinforcing our defensive air support capability," Singh said.

Meanwhile, Israeli Prime Minister Binyamin Netanyahu and Interior Minister Moshe Arbel held an in-depth situation assessment Thursday on the activities of the IDF Home Front Command since the outbreak of the war.

Netanyahu was briefed on what had been done to protect the public throughout the war, and what is being done ahead of an expected confrontation with Iran and its proxies.

After the briefing at the IDF's Camp Rehavam base near Ramla, Netanyahu told the gathered commanders: "I am now finishing a visit to the Home Front Command. General, I am impressed by the important work done so far. This is, of course, part of our preparation for what's to come. Israel is at a very high level of readiness for any scenario — in both defence and offence. We will exact a very heavy price for any act of aggression against us from any arena.”

The prime minister then spoke about the recent targeted killings of Hamas and Hezbollah leaders and said: “We have set a simple principle: Whoever harms us, we harm them.”

The Home Front Command issued a public statement on social media stating that as of now, there are no special regulations or instructions. However, it added that there are five recommended things that people could do to better prepare themselves should the need arise. They are:

1: Know where a safe room/protective area is that you can get to in the time allotted in your region.

2: Make sure that it is prepared and ready for an emergency.

3: Know what the proper instructions are for how to act if you are travelling by car or in an open area and an emergency occurs.

4: Talk to your relatives and neighbours, listen to their concerns, and explain to them the current situation in a way that will help them alleviate their concerns.

5: Double-check all information before you spread it around. Do not repeat rumours, and listen only to information coming from official sources.