Five years after US Navy SEALs killed the most wanted terrorist Osama bin Laden in Pakistan, the threat posed by violent extremists to global security is far from receding.
Though the death of bin Laden, nearly a decade after his group Al Qaeda attacked the US on September 11, 2011, was then hailed by US President Barack Obama as "the most significant achievement to date" in US effort to defeat Al Qaeda, the US counterterrorism effort in the post-bin Laden era got bogged down on another frontline.
From West and North Africa to South Asia, extremist groups have been lining up to declare allegiance to either Al Qaeda or the Islamic State (IS), once an Al Qaeda associate founded after the US invasion of Iraq in 2003.
Moreover, hailing from at least 86 countries as of December, 2015, between 27,000 and 31,000 people had travelled to Syria and Iraq to join the IS and other violent extremist groups, according to data provided by New York-based security consultancy The Soufan Group.
In its initial report entitled Foreign Fighter in Syria, which was released in June 2014, The Soufan Group identified about 12,000 foreign fighters from 81 countries.
"The increase (in foreign recruits) is an evidence that efforts to contain the flow of foreign recruits to extremist groups in Syria and Iraq have had limited impact," said the consultancy in its latest report in December.
With the aid of modern information technology, the IS has also been reaching out to its sympathizers across the world for "lone-wolf" attacks at home.
"This is sort of the new normal," said US Federal Bureau of Investigation Director James Comey last year after ten people were arrested and charged in connection with plotting attacks inspired by the IS.
Echoing US law enforcement and intelligence leaders, Obama also said last December in the wake of the shooting rampage in southern California which claimed 14 lives that the terrorist threat had already evolved into a new phase where "terrorists turn to less complicated acts of violence like the mass shootings that are all too common in our society."
The resurgence of extremist groups may seem puzzling to many, but the underlying reason is clear.
While the goal of the war launched by the US was supposedly to eliminate terrorism, the fear and hatred those foreign "meddlers" have fueled in the Middle East has created a breeding ground for extreme terrorism.
Nothing could serve as a better example than the free fall of Libya into chaos and another potential hotbed of extreme terrorism after the multinational military intervention mainly organized by then US secretary of state Hillary Clinton.
Calling Clinton the "chief architect" of the botched US Libya policy, Republican lawmaker Peter Roskam revealed last October at a high-profile hearing on the 2012 Benghazi attack that Clinton insisted on the US involvement in Libya despite grim warnings and opposition from senior US diplomats.
"(Stephen Mull, then executive secretary of the State Department) said this, 'In the case of our diplomatic history, when we've provided material or tactical military support to people seeking to drive their leaders from power, no matter how just their cause, it's tended to produce net negatives for our interests over the long term in those countries,'" quoted Roskam from newly obtained communications from Clinton's private server.
"They (US senior diplomats) were pushing back, but you overcame those objections," said Roskam, adding that Vice President Joe Biden, then Defense chief Robert Gates as well as the National Security Council also opposed military actions in Libya.
Unfortunately, Washington paid little attention to exploring the root causes of terrorism.
The war on terror will be never-ending if Washington fails to eliminate the root causes of terrorism and extremism.
The author is a writer with the Xinhua News Agency. The article first appeared on Xinhua. opinion@globaltimes.com.cn