By Jamie Crawford, reporting from Aspen, Colorado

The question of whether some of Syria's stockpiles of chemical weapons have fallen out of government control is a source of great concern for the U.S. government, according to one of the nation's top intelligence officials.

"The key for us is, are we able to identify where those weapons are? Are they safe and secure, are they falling into the wrong hands," Matthew Olsen, director of the National Counterterrorism Center said Thursday at the Aspen Institute Security Forum.

But when asked by the moderator, David Sanger of the New York Times, whether there has been a clear accounting of those weapons, Olsen was non-commital.

Read all our coverage of the 2012 Aspen Security Forum

"No, not yet," he said. "This is a very sensitive time for this situation so it's an important question that we are following."

Olsen's comments were seemingly at odds with statements from other areas of the Obama administration.

"We continue to be concerned about the disposition of the Assad regime's chemical weapons," White House Press Secretary Jay Carney said Wednesday. "We believe that they are still under control of the government, and we use every opportunity to remind the Syrian government that it must maintain control of those weapons and, of course never use them."

Olsen spoke to Security Clearance after the panel and sought to clarify his remarks.

“We are monitoring the situation very closely,” Olsen said of Syria’s chemical weapons stockpile. “Right now we think that the government has control of those weapons. Nonetheless, it’s a situation we are looking at very closely to insure that those weapons that the government has don’t fall into the wrong hands.”

In his comments alongside his immediate predecessor, Michael Leiter, Olsen said there is still a great concern that members of al Qaeda in Iraq may be exploiting the instability in Syria, crossing the border to sow even more chaos.

"It's a difficult picture because of the nature of the opposition in Syria is an intelligence challenge," he said, saying questions remain about the opposition's composition.

Syria, Olsen said, is not the only proliferation concern for the U.S. government when it comes to weapons of mass destruction.

Pakistan, which harbors the world's fastest growing nuclear arsenal, is now the focus of a joint task force between counterterrorism center and the National Counter Proliferation Center, Olsen said.

The agencies have partnered to create an "integration center" to focus on the status of Pakistan's nuclear arsenal and to ensure those weapons don't fall into the hands of al Qaeda or other militant organizations operating inside Pakistani territory.

"The idea is we need to make sure we are covering the scene between proliferation and terrorism when it comes to" weapons of mass destruction, Olsen said. He added that the task force reports regularly to the heads of both agencies, who meet frequently to discuss the issue.

As the question turned to Iran, Leiter said the threat emanating from Tehran and its ally Hezbollah has grown over time.

"What has been a relatively hot war has gotten hotter," he said, citing the recent plot to assassinate the Saudi ambassador to the United States in Washington. That plot has been attributed to both Iran and Hezbollah, as well as the ongoing shadow war between Iran and Israel.

Leiter said the confrontation with Iran and Hezbollah is nothing new, citing their support for targeting U.S. forces in Iraq and Afghanistan with improvised explosive devices and other attacks. "The Iranians have considered this a shooting war for some time," Leiter said.

"Those are significant developments from our perspective," Olsen added.

Security Clearance: Your source for national security news and analysis