Updated

Senior officials in the Obama administration and the United Nations have touted as a major arms control success story the fact that an estimated 92 percent of the Syrian regime’s declared stockpile of chemical weapons and related materiel have been removed from the country and destroyed, as agreed under the terms of a multilateral accord finalized last September.

That accord required the entire arsenal to be disposed of before June 30.
 
The remaining eight percent of the Syrian stockpile, the Assad regime has informed inspectors for the joint United Nations/Organization for the Prohibition of Chemical Weapons (OPCW) team, is contained in a storage facility located in an area presently controlled by armed rebel groups.

In a letter to the president of the U.N Security Council dated May 23, U.N. Secretary General Ban Ki-moon stated that "a military operation [will be] required to access the facility in order...to allow safe extraction of the chemical weapons material."

As a consequence, Ban added, “some activities related to the elimination of the chemical weapons programme of the Syrian Arab Republic will continue beyond 30 June...for a finite period of time."
 
Asked about the deadline, State Department spokesperson Jen Psaki appeared to reject the fact that it will not be met. “The deadline hasn't been missed,” Psaki told reporters on Friday, "the June 30th deadline.”
 
Secretary of State John Kerry this week told “PBS NewsHour” that he is confident the entire declared stockpile, including the remaining eight percent, will be destroyed. “There's one last transfer that has to take place to get to 100 percent,” Kerry said. “I believe it will take place.”
 
In the meantime, two deadly chlorine attacks were reported last month. Using chlorine as a weapon is prohibited by the Chemical Weapons Convention that Syria joined in 2013.

While chlorine is not technically considered a chemical weapon, experts consulted by Fox News suggested that simply removing and destroying all that the Assad regime cited in its declaration will not mean the end of the Syrian chemical weapons program.

“They also have facilities in which they produce these chemical agents,” said David Schenker of the Washington Institute for Near East Policy. “Some have been declared but not all of them are open for access to the chemical weapons group that is on the ground.

For years Syria denied the existence of a chemical weapons program, raising concerns that Damascus' claim it had declared its entire stockpile was doubtful.

“This is not like UNSCOM and special inspections in Iraq,” Schenker added, referring to the weapons inspections conducted prior to the toppling of Saddam Hussein. “The Syrians don’t have to let the inspectors into every site.”
 
Speaking in Damascus last month, Sigrid Kaag, the Dutch diplomat overseeing the disposal effort for the U.N. and OPCW, said her team has been working with the Syrian government to clarify and address "discrepancies and anomalies" in the regime's declaration.
 
Kaag is set to brief the Security Council on Wednesday morning. Western intelligence officials are said to believe that the Assad regime never declared the entirety of its program.

Western diplomats have been reluctant to raise the issue out of concern that doing so might have the effect of disrupting the ongoing process of getting the Syrians to dispose of that which they have formally declared.

Fox News’ Jonathan Wachtel contributed to this story