A formal pact between al Qaeda's Iraqi faction and Islamic militants in Syria could be the nail in the coffin for possible U.S. military intervention in the two-year Syrian civil war.
Formation of the so-called "Islamic State in Iraq and Levant" signaled the expanding influence of AQI in the region and the growing strength of JAN among the ranks of Syrian rebels battling to oust longtime President Bashar Assad.
The pact also likely extinguished any possibility for American military action or support for rebel forces in Syria, since the deal between AQI and al Nusra quells any doubt that al Qaeda has secured a foothold in the country.
Defense Department and U.S. intelligence officials have been wary of infiltration of anti-Assad forces by JAN fighters and other militant groups -- with the support of AQI -- into the Syrian opposition since the early days of the uprising.
Those concerns have been the major roadblock in possible U.S.-led efforts to provide small arms and heavy weaponry to anti-Assad forces, due to fears those weapons could end up in the hands of al Qaeda fighters.
But as the civil war in Syria enters its third year, congressional pressure on the Obama administration to provide military support for the rebels has ramped up significantly.
Senate Armed Services Committee chief Carl Levin (D-Mich.) is one of several Democrats who have begun to break ranks with Obama, calling for U.S. military and intelligence officials to take action in Syria.
Former Defense Secretary Leon Panetta told Congress earlier this year that the Pentagon supported arming the Syrian opposition, despite concerns about al Qaeda influence in the country, but was overruled by the White House.
Thursday's announcement, however, gives the Obama administration the political cover needed to deny military action in Syria and continue its strategy of diplomacy to oust Assad from power.
On the other hand, the formal ties between AQI and al Nusra could give Washington the green light to begin taking out JAN fighters inside Syria and Iraq.
Iraqi intelligence officials are reportedly considering allowing U.S. armed drones to carry out airstrikes along the country's volatile border with Syria against AQI and al Nusra targets.
Iraq reportedly requested the drone strikes after gunmen from al Qaeda's Syrian and Iraqi factions ambushed a convoy of Iraqi and Syrian troops along the border earlier this month.
Washington confirmed to The Associated Press that Baghdad inquired about having U.S. drones take out targets along the Syrian border, but no formal request had been made to the CIA or the Defense Department.
Last December, State Department officials placed JAN on its list of active terrorist organizations -- placing the group on par with groups such as Iranian-backed Hezbollah, Hamas and the Haqqani Network in Pakistan.
But American intelligence leaders may opt against such drone strikes or other covert action to take out AQI and al Nusra targets, instead expecting that internal divisions will break apart the recently unified terror factions from the inside out.
Divisions are already forming between al Qaeda's Iraqi cell and al Nusra's senior leadership, as well as the Sunni opposition groups that make up the majority of the Syrian rebel forces.
On Friday, Jabhat al-Nusra’s leader, Abu Mohammed al-Jawalani, said he had not been informed of the deal with AQI until Thursday's announcement.
Jawalani vowed the group would continue to back the Syrian opposition to topple Assad, and not fight to overthrow the embattled leader just to bring al Qaeda to power in Syria.
Even with the backing of AQI, the Sunni-dominated Syrian opposition is beginning to push back against al Nusra's influence in Syria, Director of National Intelligence James Clapper told Congress Thursday.
"There are increasing indications though that the moderate Islamists are . . . not comfortable" with AQI and al Nusra joining forces, attempting to co-opt the opposition to establish al Qaeda in Syria, Clapper told House Intelligence Committee members.
"There are indications of divisiveness among the Sunni opposition groups," he added. "So how that will play out, hard to say. That's something we're watching carefully."