The first purported message from Mojtaba Khamenei, the newly installed supreme leader of Iran, was read on state TV on Thursday.

Khamenei did not appear in the address, which was read by a woman.

The message said that the “key is to overcome our enemy,” and he said attacking neighboring countries was necessary because they’re cooperating with the U.S.

He said several of his family members were killed besides his father, including his wife, his sister and his sister’s child.

He also vowed to avenge the "martyrs," including those killed in the strike near an Iranian girls' elementary school.

Mojtaba Khamenei was chosen on Sunday to replace his father, Ali Khamenei, the former supreme leader, who was killed on the first day of the U.S.-Israeli strikes.

Energy Secretary Chris Wright told CNBC that the U.S. Navy is “not ready” to escort oil tankers through the Strait of Hormuz, but he said it could happen by the end of the month.

"It will happen relatively soon, but it can't happen now,” Wright said. “We're simply not ready. All of our military assets right now are focused on destroying Iran's offensive capabilities and the manufacturing industry that supplies their offensive capabilities.”

In an interview on CNN, Wright was asked if the U.S. can declare victory without the Strait of Hormuz being reopened.

“No, the Strait of Hormuz needs to be and will be reopened. The U.S. military is there for the -- is there to solve a long-term problem,” he said, pinning the blame on the Iranian regime.

-ABC News’ Emily Chang

Mojtaba Khamenei, the newly installed supreme leader of Iran, is expected to issue a "strategic" message on Thursday, Iranian state media reported.

Khamenei was chosen on Sunday to replace his father, Ali Khamenei, the former supreme leader, who was killed on the first day of the U.S.-Israeli strikes.

-ABC News' Joe Simonetti

Israel's military is preparing to expand activity in Lebanon, Israeli Defense Minister Israel Katz said on Thursday.

"I warned the Lebanese president that if the Lebanese government does not know how to control the territory and prevent Hezbollah from threatening the northern communities and firing at Israel -- we will take the territory and do it ourselves," Katz said in remarks at a military operations center in Tel Aviv.

"The prime minister and I instructed the IDF to prepare to expand IDF activity in Lebanon and restore peace and security to the northern communities," Katz added.

An Israeli military official told ABC News on Thursday that more than 200 rockets were fired toward Israel from Lebanon, where the Israel Defense Forces are targeting Hezbollah infrastructure and members.

-ABC News' Jordana Miller and Dana Savir

The Pentagon identified the six service members killed when a U.S. KC-135 refueling aircraft crashed in western Iraq on Thursday.

Three of the Air Force airmen were assigned to the 6th Air Refueling Wing, MacDill Air Force Base in Florida.

• Maj. John A. Klinner, 33, of Auburn, Alabama
• Capt. Ariana G. Savino, 31, of Covington, Washington
• Tech. Sgt. Ashley B. Pruitt, 34, of Bardstown, Kentucky

The other three airmen were assigned to the 121st Air Refueling Wing at Rickenbacker Air National Guard Base in Columbus, Ohio.

• Capt. Seth R. Koval, 38, of Mooresville, Indiana
• Capt. Curtis J. Angst, 30, of Wilmington, Ohio
• Tech. Sgt. Tyler H. Simmons, 28, of Columbus, Ohio

The crash, which involved another KC-135 tanker, is still under investigation.

The aircraft was lost while flying over friendly airspace in western Iraq March 12 during Operation Epic Fury, according to U.S. Central Command.