First photo emerges of the 'building where Haniyeh was killed'

The commander of Israel's Air Force, Tomer Bar, warned those who plan "to harm the citizens of the State of Israel," following the assassination of a Hezbollah and a Hamas official in Beirut and Tehran.

“This is another message to our enemy in the entire Middle East," he said in a statement Wednesday, "there is no point that is too far for us to attack,” he said in a statement.

Bar said dozens of Israeli aircrafts are “prepared and ready in a matter of minutes, for any scenario, in any arena."

Israeli prime minister Benjamin Netanyahu delivered a brief televised statement, following to high profile assassinations in Lebanon and Iran in a day.

He did not mention Haniyeh, who was killed early hours of Wednesday in Tehran, but said his country had hit "the three Hs" hard: Houthis, Hamas, Hezbollah.

In what seemed to be an implicit warning against any retaliatory action, he said, "they will pay a price if there is any aggression against us, wherever that theater is."

He also reminded Israelis that the days ahead would be "very challenging."

Iran's former nuclear negotiator threatened Israel with paying a 'heavy price' for the assassination of Hamas leader Ismail Haniyeh in Tehran.

"Undoubtedly, the Israeli occupying regime...will not achieve its ominous goal of putting obstacles in the path of Iran's new government at the outset of its endeavor."

Araghchi has been deputy foreign minister before and is said to be a serious contender for the top post in Iran's new administration under Masoud Pezeshkian.

Analysts and Hamas officials have told Reuters that Haniyeh's most likely successor is Khaled Meshaal, his deputy-in-exile who lives in Qatar.

Mashal headed Hamas politburo until 2017. He was widely recognized as the organizations top man for more than a decade, following the assassination of Hamas leader Abdel Aziz al-Rantisi in 2004.

Mashal narrowly survived an attempt on his life in Jordan ordered by Netanyahu in 1997.

Analysts say Mashal's relationship with Iran's leaders was not as warm as that of Haniyeh, although he had also travelled to Tehran on several occasions.

Iran's ambassador to the UN has asked the Security Council to convene an emergency meeting to address “Israeli aggression and terrorist attacks”.

Hamas leader Ismail Haniyeh was killed in Tehran early hours of Wednesday local time. The assassination, Amir Saeid Iravani wrote in a letter Wednesday, "suggests an intention to escalate conflict and expand the war through the entire region."

He urged the international community to take “decisive action" to "hold the perpetrators accountable.”