Iran live updates: Trump calls GOP backers of war powers resolution 'grandstanders'

Iranian state television on Thursday broadcast the reading of a new statement purportedly written by Iranian Supreme Leader Mojtaba Khamenei, who has not been seen in public since he was appointed supreme leader in March, succeeding his father -- Ayatollah Ali Khamenei -- who was killed in the opening hours of the U.S.-Israeli war with Iran.

The statement was read by an Iranian cleric to the public in the mausoleum of Ayatollah Ruhollah Khomeini -- the leader and founder of the Islamic Republic -- in Tehran, on the 37th anniversary of his death.

"Defending the oppressed is not only an Islamic duty, but a human and Iranian one as well. And the ruling establishment in Washington has a problem with this nation's identity, independence, and refusal to surrender," Khamenei's message read.

"The Iranian nation, with its new mission alongside the resistance front, has become a source of pride for free nations," it added.

"The [U.S.-led] hegemonic system which established Israel nearly 80 years ago does not bear a strong, independent and privileged Iran on the eastern borders of the void and fake 'Greater Israel,'" the statement continued.

Khamenei claimed that the U.S. and Israel had sustained "heavy blows" in its conflict with Iran.

-ABC News' Somayeh Malekian

A United Nations Interim Force in Lebanon peacekeeper died on Thursday morning after sustaining injuries in a Wednesday night mortar attack on a position near Marjayoun in southeastern Lebanon, the force reported.

Two other peacekeepers were injured in the attack and are undergoing treatment at a UNIFIL base, the force said in posts to social media.

"UNIFIL has launched an investigation to ascertain the exact circumstances that led to this tragic incident," the force wrote.

"UNIFIL has detected an increasingly high number of trajectories and impacts in South Lebanon. The violence must end," it added.

Israel and Hezbollah continued to launch attacks through Wednesday night and into Thursday morning despite an agreement on the implementation of a ceasefire between Israeli and Lebanese leaders announced by the State Department on Wednesday.

The deal announced on Wednesday is contingent on a "complete cessation" of Hezbollah fire and the evacuation of all its forces from the South Litani Sector, according to the statement.

But both Israel and Hezbollah continued to launch attacks into Thursday.

Israel Defense Forces spokesperson Avichay Adraee said in a post to X addressing southern Lebanese residents on Thursday, "The fighting in southern Lebanon continues as the Israel Defense Forces continue to target Hezbollah facilities and infrastructure located in your villages and nearby."

Adraee also issued fresh evacuation warnings for residents of southern Lebanon. “The IDF continues to target Hezbollah terror infrastructure located in and near the area south of the Zahrani River,” he wrote.

Lebanon's National News Agency said that three people were injured when a car was attacked while traveling in the south of the country. NNA also reported an Israeli airstrike on a town in the southern Tyre district.

Hezbollah, meanwhile, claimed overnight attacks on "gatherings of Israeli enemy soldiers" in multiple locations in the south of the country.

In his appearance before Congress on Wednesday, Secretary of State Marco Rubio described the tempo of what he called "kinetic actions" between the U.S. and Iran in recent days, which he characterized as a U.S. response to Iranian provocations.

"That is some commercial ship that didn't pay a toll and starts to move. That ship comes under attack by a drone. We shoot down the drone. In some cases, not only do we shoot down the drone, but we hit the launcher of the drone, so they can't hit the ship a second time," Rubio said.

"The Iranians then respond by launching two missiles or three at some base in the region as their response. And that's what you've seen play out three of the last four nights with regards to this," he added.

Rubio also discussed the nuclear element of the ongoing negotiations with Iran, saying that any new nuclear agreement would invoke legislation that would put the pact before Congress.

In response to a question from Sen. Lindsey Graham, Rubio said the administration wants a deal that would allow the U.S. to punish Iran for its continued support for the Hezbollah militia in Lebanon, but stressed that the "primary threat here is the nuclear weapons ... they can never have a nuclear weapon."

Uranium enrichment monitoring, Rubio added, will be "critical for any deal to be successful."

Rubio also told senators that the ongoing talks with Tehran are being complicated as the Iranian government is "fractured." He estimated it takes some between seven and 10 Iranian negotiators to pass proposals.

Rubio said this week that it often takes "three to five days to get a response" from the Iranian leadership.

ABC News' Shannon K. Kingston and Christopher Boccia