US President Joe Biden has called the death of Hezbollah's leader Hassan Nasrallah from an Israeli airstrike a "measure of justice for his many victims, including thousands of Americans, Israelis, and Lebanese civilians."

In a statement released on Saturday, Biden said Nasrallah and the terrorist group he led, Hezbollah, were responsible for killing hundreds of Americans over a four-decade reign of terror.

Biden added that the United States fully supports Israel's right to defend itself against Hezbollah, Hamas, the Houthis, and any other Iranian-supported terrorist groups.

The president revealed that he had directed US Defense Secretary Lloyd Austin to further enhance the defense posture of US military forces in the Middle East region to deter aggression and reduce the risk of a broader regional war.

He added that the US's aim is to de-escalate the ongoing conflicts in both Gaza and Lebanon through diplomatic means.

The US State Department on Saturday ordered some US embassy staffers and their families in the Lebanese capital, Beirut, to leave the country.