In the wake of a recent Russian-U.S. deal averting American airstrikes, Syria has begun to answer questions about its chemical weapons stockpile. One thing inspectors don't have the mandate to ask is where those weapons came from in the first place. But evidence already out there suggests Syria got crucial help from Moscow and Western European companies.

When Secretary of Defense Chuck Hagel was asked recently about the origins of Syria's chemical weapons, he said, "Well, the Russians supply them." Hagel's spokesman George Little quickly walked back that statement, saying Hagel was simply referring to Syria's conventional weapons. Syria's  chemical weapons program, Little explained, is "largely indigenous."

But declassified intelligence documents suggest Hagel, while mistakenly suggesting the support was ongoing, was at least pointing his finger in the right direction.

A Special National Intelligence Estimate dated Sept. 15, 1983, lists Syria as a "major recipient of Soviet CW [Chemical Weapons] assistance." Both "Czechoslovakia and the Soviet Union provided the chemical agents, delivery systems, and training that flowed to Syria." "As long as this support is forthcoming," the 1983 document continues," there is no need for Syria to develop an indigenous capability to produce CW agents or materiel, and none has been identified."

Soviet support was also mentioned, though with less details, in another intelligence estimate dated Feb. 2, 1982. That report muses about the U.S.S.R.'s motivation for exporting chemical weapons to Syria and other countries. The Kremlin saw gas as useful for allies fighting against insurgencies: For the countries that had actually used it in combat 2013 Kampuchea, Laos, Afghanistan and Yemen - the authors conclude that the Soviet Union saw it as a way of "breaking the will and resistance of stubborn guerrilla forces operating from relatively inaccessible protected sanctuaries."

The 1982 report goes on to say: "The Soviets probably reasoned that attainment of these objectives 2013 as quickly and cheap as possible 2013 justified use of chemical weapons and outweighed a small risk of exposure and international condemnation." Last week, German newspaper Süddeutsche Zeitung reported that intelligence sources in the country are convinced blueprints for four of the five Syrian poison gas plants came from Moscow.

Evidence gathered from what we now know was a sarin attack last month is also suggestive. According to an investigation by Human Rights Watch, one of the weapons used in the attack was "a Soviet-produced 140mm rocket." Meanwhile, the UN's own report shows a picture of Cyrillic letters on the remnants of the rocket.

It's impossible to know the exact extent of Soviet and Russian help. U.S. intelligence was not particularly focused on the Syrian program, says Gary Crocker, a proliferation specialist at the State Department's Bureau of Intelligence and Research in the 1970s and 1980s. Most analysts did not know much about its program: "Detailed information on the Syrian program was only accessible to very high level intelligence officials," Crocker said.

There are also indications that the Soviets grew increasingly uneasy with Syria's ability to deliver the deadly gas by long-range missile. Concerned about Syria's buildup, the head of the Soviet chemical warfare corps, General Vladimir Pikalov,flew to Syria in 1988. According to reports from the time, he decided against supplying the country with SS-23 missiles, which would have been able to deliver poison gas deep into Israel.

But the Soviets don't appear to be the only ones who provided some help.

"Soviets provided the initial setup, then the Syrians became quite proficient at it. Later, German companies came in," Crocker said.

As then- CIA director William Webster said in Senate testimony back in 1989: "West European firms were instrumental in supplying the required precursor chemicals and equipment." Asked why the companies did it, Webster answered: "Some, of course, are unwitting of the ultimate destination of the products they supply, others are not. In the latter case, I can only surmise that greed is the explanation."

Indeed, Syria received precursor chemicals from the West until well into the last decade. Last week, the German government acknowledged that between 2002 and 2006, it had approved  the export to Syria of more than 100 tons of so-called dual-use chemicals. Among the substances were hydrogen fluoride, which can be used to make Teflon,  and also sarin. The exports were allowed under the condition that Syria would only use them for civilian purposes. The British government also recently acknowledged exports of dual-use chemicals to Syria.

Both the British and German governments said there's no evidence the chemicals were used to make weapons.

It's not the first time Germany may have turned a blind eye to potentially dangerous trade. In the 1980s, for instance, German and French companies were crucial in building poison gas plants in Iraq and Libya . Stricter export controls in Europe were only installed after a web of companies that supplied the chemical weapons programs in the Middle East was exposed in the late 1980s. The New York Times embarrassed the German government by revealing the connection between German company Imhausen-Chemie and a Libyan poison gas plant in Rabta. (Times columnist William Safire German later called the plant " Auschwitz-in-the-sand.")

In the following years, German authorities indicted more than 150 managers of companies involved in Saddam Hussein's program, which he had used to kill thousands of Kurds. According to one report, from the late 201890s, more than half of the proceedings were stopped. Most of those that went to trial were acquitted or paid fines, a handful received jail time.

Just how deeply were German companies involved in Syria's program? We may never know.  A long-ago proposal by the German Green party to install a fact-finding commission to comprehensively investigate the web of German companies supplying Middle Eastern states 2013 and government knowledge of these exports - was voted down by all other parties in parliament.

This article originally appeared on ProPublica