Lindsey Graham, a US Republican senator, has urged the United States government to quickly adjust its policies to prevent a repeat of the 9/11 attacks.
Graham wrote on his Twitter account, "A terrorist safe haven in Afghanistan is a formula for disaster.”
According to him, radical Islamic presence is growing in Afghanistan.
Graham quoted the Federal Bureau of Investigation (FBI) director Christopher Wray as saying that al-Qaeda and other radical Islamic groups very much desire to hit the American homeland.
Ayman al-Zawahiri, the leader of al-Qaeda, was targeted and killed in a US drone attack on the balcony of a safe house in the heart of Kabul on Sunday.
His death has been welcomed by American politicians and the international community, but the concerns about al-Qaeda's terrorist activities in the country remains.
The US government has cautioned US citizens of possible retaliatory attacks by the al-Qaeda. The US State Department said on Tuesday that al-Qaeda may launch retaliatory attacks against US citizens after the death of their leader.
The ministry urged American citizens to be cautious when traveling to other countries.
The US State Department believes that "due to Ayman al-Zawahiri's death, there is more capacity for anti-American violence”.