WASHINGTON: The war in Syria poses the greatest threat to US security because of the risk of the government falling and the country becoming a weapons-rich haven for Al-Qaeda, a CIA official says.

CIA second-in-command Michael Morell gave the assessment in an interview published Tuesday by the Wall Street Journal as he prepares to retire after 33 years with the agency.

Morell said there are now more foreign fighters flowing into Syria each month to take up arms with al Qaeda-affiliated groups than there were going to Iraq to fight with al Qaeda at the height of the war there.

The Syrian government's weapons “are going to be up for grabs and up for sale” as they were in Libya when Moamer Kadhafi fell, he added.

“It's probably the most important issue in the world today,” he said of the war in Syria, “because of where it is currently heading” -- toward the fall of the government of President Bashar al-Assad, according to Morell.

Morell also said the violence in Syria has the potential to spill across borders into Lebanon, Jordan and Iraq.

Morell told the Journal that second on his list was Iran, followed by the global al Qaeda threat, North Korea, and cyber warfare.

On al Qaeda, he said the United States had “significantly degraded” the group's capabilities in Pakistan and Afghanistan.

But the terror network has also scored victories, such as its dispersal, which he said has spread its ideology and global reach.

Morell will be replaced by Avril Haines, a 43 year old White House lawyer.