Israel likely used United States-made 900kg (2,000-pound) bombs in the strike that killed Hezbollah leader Hassan Nasrallah and levelled residential buildings in Beirut’s southern suburbs earlier this week, The Washington Post reports.

Citing three experts who analysed videos of Friday’s strikes, posted by the Israeli Air Force, the Post said on Sunday that at least some of the bombs were US-made “BLU-109s and JDAM guidance kits”.

BLU-109s are bunker-buster heavy bombs and JDAM kits are guidance systems that attach to munitions to help attack a specific target.

A 2,000-pound bomb has a destruction radius of 35 metres (115 feet), according to the Project on Defense Alternatives (PDA), which conducts defence policy research and analysis.

Nasrallah, Hezbollah’s longtime chief, was killed in Friday’s strike on the group’s underground headquarters. Israel dropped what local media said were “bunker-busting” bombs and flattened about six buildings, while trying to kill Nasrallah.

The attack also devastated the entire neighbourhood, turning several apartment buildings into rubble.

The Washington Post quoted NR Jenzen-Jones, the director of Armament Research Services – a group providing analysis on arms and munitions – as saying that “initial available videos of the strike show that numerous large air-delivered bombs were used”. He added that they were meant to penetrate through a “heavily protected space”.

US officials have repeatedly said that they received no prior notice about Friday’s Israeli strikes in Lebanon. But US President Joe Biden and his Vice President Kamala Harris have welcomed the assassination of Nasrallah, calling it a “measure of justice”.

The Biden administration has been facing increasing criticism from rights advocates over its unconditional arming of Israel, which has killed more than 41,500 people in Gaza and hundreds in Lebanon.

Washington stopped a single shipment of 2,000-pound bombs to Israel earlier this year over concerns about their use in densely populated areas in Gaza. The Biden administration later approved the release of 500-pound (227 kg) bombs which were part of the same transfer.

Israel’s Ministry of Defense said on Thursday that it had secured an $8.7bn US military aid package – days after it launched a massive attack that killed hundreds of people in south Lebanon and Beirut and displaced hundreds of thousands of civilians.

Separately, the Pentagon said on Sunday that it has “increased the readiness of additional US forces to deploy” to the Middle East.

“The United States retains the capability to deploy forces on short notice,” the Pentagon said in a statement.

“The Department of Defense continues to maintain a significant amount of capability in the region and to dynamically adjust our force posture based on the evolving security situation,” it added.

Later in the day, Biden said he would speak with Israeli Prime Minister Benjamin Netanyahu, stressing that an all-out war in the Middle East must be avoided.

“It has to be,” Biden told reporters as he boarded Air Force One for Washington. “We really have to avoid it.”

The president’s statements come as Israeli air strikes across Lebanon intensified on Sunday. The Biden administration has maintained support for Israel and its attacks across the region as Washington continues to call for de-escalation.