Idlib Jabhat al-Nusra tank
Islamist Syrian rebel group Jabhat al-Nusra members pose on a tank in northern Idlib province.Reuters

A new report condemns the United States' single-minded focus on Daesh, saying the policy is misguided. "Any strategy that leaves Jabhat al-Nusra in place will fail to secure the American homeland," said the Institute for The Study of War and American Enterprise Institute.

Islamic State and al-Nusra attacks could threaten the global economy and provoke "Western societies to impose severe controls on... freedoms and civil liberties," warns the report, which claims that "American values and way of life" are in danger.

Jabhat al-Nusra hasn't undertaken attacks in the West unlike Islamic State, says Fred Kagan, one of the authors of the report. He believes al-Nusra has made a tactical decision not to attack the West for the time being.

"While Isis is flashier... both represent an existential threat, both wish to attack the homeland, both seek the mobilisation of Muslim communities against the West," he said.

However, the Director of National Intelligence James Clapper told the Senate intelligence committee in January 2014 that al-Nusra "does have aspirations for attacks on the homeland."

Read the full report here

Al Qaeda and ISIS: Existential threats to the US and Europe

Al Qaeda's Syrian branch represents a longer-term and more tenacious threat than Isis and that targeting al-Nusra would be more difficult than targeting Islamic State.

"Al-Nusra is quietly intertwining itself with the Syrian population and Syrian opposition... They are waiting in the wings to pick up the mantle of global jihad once Isis falls," he said.

The key findings of the report state that the Syrian al Qaeda affiliate Jabhat al Nusra poses one of the most significant long-term threats. The Islamic militant group has established an expansive network of partnerships with local opposition affiliates that are fiercely loyal to the jihadist organisation. Jabhat al Nusra's destruction is one of the highest priorities to defend the United States and Europe from al Qaeda attacks.

The US State Department says over 35,000 foreign fighters from 100 countries have crossed into Syria to take part in the bloody conflict. The al-Nusra Front attracts the second-highest amount of foreign fighters, ranking only behind Islamic State, according to Nick Heras of the Centre for a New American Security.