US intelligence agencies have concluded that Syria’s Bashar Assad did not give up all of the chemical weapons in his possession in 2013, the Wall Street Journal reported Friday.

According to the report, Assad tucked away “caches of even deadlier nerve agents” than the ones relinquished. The weapons currently run the risk of falling into the hands of the Islamic State or, alternatively, Israel’s arch-foe Hezbollah, according to US intelligence sources.

The detailed report also revealed the reticence of international inspectors and world powers in pressing the regime for further information, amid fears Assad would reconsider the international bid to rid Syria of its chemical weapons arsenal.

Assad’s regime agreed to an international plan, following a 2013 sarin attack on a Damascus suburb that sparked a global outcry. The United States threatened military action against Damascus over the attack, but held off following the disarmament agreement.

Members of a UN investigative team take samples near the site of an alleged chemical weapons attack, in Syria, August 28, 2013. (photo credit: AP/United Media Office of Arbeen)

Members of a UN investigative team take samples near the site of an alleged chemical weapons attack, in Syria, August 28, 2013. (photo credit: AP/United Media Office of Arbeen)

Last month, the world’s chemical weapons watchdog said all effluents from Syria’s neutralized chemical weapons arsenal had been destroyed. Of the 1,300 metric tons of Syria’s declared chemical weapons, only 16 metric tons of hydrogen fluoride remained to be destroyed at a facility in Port Arthur in Texas, according to the Organization for the Prohibition of Chemical Weapons.

The international operation to rid Syria of its chemical weapons was welcomed by the US as a success, even as various reports emerged in May of additional chemical attacks in Syria and the discovery of undeclared chemical weapons.

The Wall Street Journal account said international inspectors in 2013 only entered sites declared by Syria as chemical weapons labs. Fearing Damascus would end its cooperation — and fearing for their personal safety — they were reluctant to press their hosts for more information and to demand access to other suspicious facilities.

Syrian President Bashar Assad gestures during an interview with Italy's RAI News 24 TV, at the presidential palace in Damascus, Syria, Sept. 29, 2013 (photo credit: AP/SANA)

Syrian President Bashar Assad (photo credit: AP/SANA)

“Because the regime was responsible for providing security, it had an effective veto over inspectors’ movements. The team decided it couldn’t afford to antagonize its hosts, explains one of the inspectors, or it ‘would lose all access to all sites.’ And the inspectors decided they couldn’t visit some sites in contested areas, fearing rebels would attack them,” the report said.

“Under the terms of their deployment, the inspectors had access only to sites that the Assad regime had declared were part of its chemical-weapons program. The US and other powers had the right to demand access to undeclared sites if they had evidence they were part of the chemical-weapons program. But that right was never exercised, in part, inspectors and Western officials say, because their governments didn’t want a standoff with the regime,” continued the report.

The international inspectors chose to cooperate with the Syrian regime’s demands, with one inspector saying “it was a question of priorities.”

The convoy of a UN team of weapons inspectors, who concluded its almost week-long mission in Syria, arrive at Rafik Hariri international airport in Beirut, Lebanon, Monday, September. 30, 2013. (photo credit: AP Photo/Bilal Hussein)

A convoy of UN weapons inspectors at Rafik Hariri international airport in Beirut, Lebanon, September. 30, 2013 (AP/Bilal Hussein)

“Members of the inspection team didn’t push for answers, worried that it would compromise their primary objective of getting the regime to surrender the 1,300 tons of chemicals it admitted to having,” the report stated. “The Syrians laid out the ground rules. Inspectors could visit only sites Syria had declared, and only with 48-hour notice. Anything else was off-limits, unless the regime extended an invitation.”

“We had no choice but to cooperate with them,” stated Scott Cairns, one of the leaders of the mission. “The huge specter of security would have hampered us had we gone in there very aggressively or tried to do things unilaterally.”

The report comes hot on the heels of the nuclear deal between Iran and world powers, under which international inspectors will not be granted “anytime, anywhere” access to suspect sites, but will merely be allowed to request access to all facilities, if they can provide proof of violations and are unsatisfied with Iran’s explanation. Altogether, the procedure put in place could take up to 24 days. Top Iranian officials in past days have made clear that there will be no access to military sites.

Better than nothing

The Obama administration nonetheless believes the Syrian operation was immensely successful, according to the report, as it destroyed a significant portion of Assad’s chemical weapons stockpile.

“The White House and State Department say last year’s mission was a success even if the regime hid some deadly chemicals… US officials say the security situation would be far more dangerous today if those chemicals hadn’t been removed, especially given recent battlefield gains by Islamists. Demanding greater access and fuller disclosures by the regime, they say, might have meant getting no cooperation at all, jeopardizing the entire removal effort,” the Journal reported.

Thomas Countryman, the assistant secretary of state for international security and nonproliferation, told the paper “it is important to keep a perspective that the most dangerous of these inhumane weapons are no longer in the hands of this dictator.”

Shifting intelligence assessments

In 2013, the CIA believed Syria’s account of its stockpile, even as other Pentagon officials cast doubt on Syria’s trustworthiness.

US and UN officials gave Syria an unofficial “B plus for truthfulness,” the report said.

“The CIA had been confident that Mr. Assad destroyed all of the chemical weapons it thought he possessed when the weapons-removal deal was struck. In recent weeks, the CIA concluded that the intelligence picture had changed and that there was a growing body of evidence Mr. Assad kept caches of banned chemicals, according to US officials,” continued the communique.

The report added that the Islamic State’s recent gains have prompted fears that Assad may unleash these chemical weapons, or hand them over to Hezbollah. Assad “hid caches of even deadlier nerve agents” than the ones he gave up.

“A new intelligence assessment says Mr. Assad may be poised to use his secret chemical reserves to defend regime strongholds. Another danger is that he could lose control of the chemicals, or give them to Hezbollah.

“If the regime collapses outright, such chemical weapons could fall into the hands of Islamic State, or another terror group,” continued the report.

Inspectors present during the 2013 visit told the paper that Syria’s chemical-weapons labs were disguised in nondescript 18-wheeler trucks, or hidden in plain sight.

It was “unlike any other program that I’ve seen or read about,” said Cairns.

At one point, the inspectors requested access to the Syrian Scientific Studies and Research Center, a Damascus site bombed by Israel in 2013. Their request was approved. In May 2014, the inspectors entered the research center, guided by a Syrian general who maintained that there were no chemical weapons being developed there. “Gen. Sharif attended the presentation, which included an Arabic-language PowerPoint. The slides explained the SSRC’s work in areas including oncology and pesticides. The skeptical inspectors urged the Syrians to come clean about all their research and development facilities,” the communique said.

In October 2014, Syria added the SSRC to the list of chemical-weapons sites. “That gave inspectors the right to visit them for examinations. Western officials say samples taken by inspectors at the sites found traces of sarin and VX, which they say confirms that they had been part of the chemical-weapons program,” the report added.

The Associated Press contributed to this report.