The recent shooting massacre in Florida has revealed the US vulnerability in tracking terror suspects to prevent similar lone wolf terror attacks.

In one of the worst shooting incidents in US history, 29-year-old Omar Mateen attacked a gay nightclub in Orlando, Florida on June 12, killing 49 people and wounding 53 others. The attacker had pledged allegiance to Islamic State (IS), the deadly terror group that has carried out a brutal attack late last year in Paris that killed 130 people, as well as to other radical groups opposed to IS.

While it remains unknown whether Mateen had any direct contact with any of these groups, it appears that he was highly influenced by IS and other radical Islamist propaganda disbursed online.

What disturbed US authorities is the fact that Mateen had been on a watch list for alleged links to terrorism. He was interviewed twice by the Federal Bureau of Investigation (FBI) for making inflammatory comments to coworkers alleging possible terror ties.

Mateen was later removed from the watch list as the FBI could not verify the substance of his comments. And he purchased the guns legally which he used in the shooting attack.

The shooting massacre raised the question of how to combat the influence of radical Islamist propaganda in the US, which has led hundreds of people in the West to join the ranks of IS.

It also casts doubts on US intelligence and law-enforcement agencies' ability to track terror suspects to prevent them from launching lone wolf attacks.

Wayne White, former deputy director of the State Department's Middle East Intelligence Office, told Xinhua that reducing the influence of dangerously radical militant Islam in the US involves multiple actions.

Harsh political rhetoric and inflammatory proposals such as shutting down Muslim immigration must tamp down, in order to reduce the US Muslim community's alienation, White said.

Indeed, presumptive Republican nominee Donald Trump in a speech the day after the attack called for a ban on immigration from countries linked to radical Islam, a proposal experts say will only isolate the US Muslim community and do little to thwart future attacks.

"We know from the experience of Muslims in even less tolerant countries like France and Belgium that such mistreatment causes homegrown Muslim extremism to spike," White said, referring to two countries that have witnessed horrific terror attacks.

American Muslims themselves must do even more to espouse moderation, heighten their awareness of potential extremism in their midst, and increase their willingness to report disturbing individual views and behavior, White said.

Laws could be toughened regarding those who assist violent extremists, he said, reflecting growing concerns that Mateen's wife had assisted him in plotting the attack in some ways. While Central Intelligence Agency Chief John Brennan on Thursday said IS is plotting to send operatives to the West to carry out more terror strikes, it remains unknown exactly how many such radicals are in the West or the US

Colin P. Clarke, an associate political scientist at the RAND Corporation, said the US needs to dedicate more resources to countering violent extremism and countering the narrative of groups like IS. Clarke added that the US advertising industry could play a role.

The author is a writer with the Xinhua News Agency. opinion@globaltimes.com.cn