al-Zawahiri was killed in a drone strike carried out by the US in Afghanistan's capital Kabul.
Former US President Barack Obama on Monday welcomed the killing of Al Qaeda leader Ayman al-Zawahiri .
al-Zawahiri was killed in a drone strike carried out by the US in Afghanistan's capital Kabul.
Obama said that the killing is proof that it ispossible to fight terrorism without being at war in Afghanistan.
"More than 20 years after 9/11, one of the masterminds of that terrorist attack and Osama bin Laden's successor as the leader of al-Qaeda – Ayman al-Zawahiri – has finally been brought to justice," Obama said.
"It's a tribute to President Biden's leadership, to the members of the intelligence community who have been working for decades for this moment, and to the counterterrorism professionals who were able to take al-Zawahiri out without a single civilian casualty.
"Tonight's news is also proof that it's possible to root out terrorism without being at war in Afghanistan. And I hope it provides a small measure of peace to the 9/11 families and everyone else who has suffered at the hands of al-Qaeda," the former US President added.
President Joe Biden announced al-Zawahiri's killing on Monday in a televised address.
"Justice has been delivered and this terrorist leader is no more," Biden said.
"The United States continues to demonstrate our resolve and our capacity to defend the American people against those who seek to do us harm. Tonight we made clear: No matter how long it takes. No matter where you try to hide. We will find you," Biden later tweeted.
al-Zawahiri was one of five signatories to Osama bin Laden's 1998 "fatwa" calling for attacks against Americans. He was one of Al Qaeda's key strategists who also served as bin Laden's personal doctor.