The United States expressed condolences Monday over the death of Iranian President Ebrahim Raisi in a recent helicopter crash, which Defense Secretary Lloyd Austin portrayed as "very unfortunate."

Matthew Miller, the spokesperson for the State Department, issued a condolence message after the helicopter carrying the president and Iran's top diplomat crashed into the country's mountainous northwestern region on Sunday.

The crash came amid tensions between the US and Iran in the midst of the war between Israel and Iran-backed Hamas militants, and the Islamic Republic's apparent support for Russia's war efforts in Ukraine.

"The United States expresses its official condolences for the death of Iranian President Ebrahim Raisi, Foreign Minister Amir-Abdollahian, and other members of their delegation in a helicopter crash in northwest Iran," Miller said.

"As Iran selects a new president, we reaffirm our support for the Iranian people and their struggle for human rights and fundamental freedoms," he added.

During a press conference, Austin said that the US had "no part" to play in the crash -- a fact that he stressed is "plain and simple."

"Regarding the death of Iran's president in the very unfortunate helicopter crash, we continue to monitor the situation," he said.

"But we don't have any insights into the cause of the accident. At this point, certainly we know the Iranians are investigating or will investigate it and we will see what the outcome is once their investigation is complete," he added.

Asked if he has directed any force posture change in the wake of the crash, the Pentagon chief said he had no announcements to make.

"This is something that we will continue to watch, and I don't necessarily see any broader regional security impacts at this point in time," he said. (Yonhap)