A recent post deleted about ten other links that I had added via edit - from a WIDE variety of reports - many of them very credible sites - like the dailymail.com.
Rather than repost those links, will let those that truly have inquiring minds search for yourselves, and choose which sites one cares to peruse.
Search terms - ISIS Sarin
Facts: The UN report on the 2013 Sarin attacks (multiple attacks, one with 1,000-1,400 casualties) does NOT assign blame Assad, nor to the rebels. That FACT shows that the UN investigation found evidence that either side could have used it. That is a very relevant fact.
Fact: The shelf life of Sarin can be weeks to months to a couple of years, depending on the impurities. HOWEVER, it can be and IS lethal for YEARS, even up to and beyond 10 years in a degraded state.
FACT: Sarin can be made in a bifurcated state - where the Sarin is actually produced in a final mixing upon use. This extends the shelf life to several years.
Fact: Sarin IED's were used in IRAQ back in the mid 2000's - although the sarin was degraded.
FACT: A cult in Japan made Sarin, and used it, back in the 1990's. The idea that sarin is too difficult to make that only 'governments' can make it is ridiculous, and is obviously refuted by historical evidence.
FACT: The rebels in Syria controlled NOT ONLY ALEPPO, but also a chemical weapons plant outside of ALEPPO. This plant was documented to be able to make CHLORINE for Assad. Anyone who does not think that a chemical plant can be easily adapted to make other chemicals just isn't thinking clearly.
FACT: Sarin possession by MUSLIM TERRORISTS is viewed by MANY, if not most, European Nations as a very credible threat - and many of those nations have taken preventive and prophylatic measures against this threat.
FACT: Lybia had chemical weapons, and manufacturing plants. The 2013 Sarin attack could have been supplied to ISIS via Lybia (which is now under the control of Al Queda and ISIS and was so in 2013). Furthermore, Lybia could ALSO be supplying sarin to the 'rebels' in Syria today.
FACT: Two chemical weapons plants in IRAQ still exist - both of them under ISIS control.
FACT: Iran is supporting the Al Nusra and Hezbollah rebels in Syria. Iran certainly could be supplying the rebels with SARIN.
Conclusion: There are SEVERAL means by which the rebels (ISIL/ISIS) could get their hands on sarin - either fresh stuff, degraded stockpiles, bifurcated sarin, or sarin that they themselves are making. And there are several avenues by which they (ISIS/ISIL) could be getting the raw materials for manufacture.
IF a group of cultists, over 20 years ago, could make sarin - I guaran-damn-tee ya that Isis can easily do so today.
If you wish to not acknowledge this - so be it. The links to reports are readily available. Believe it or not - up to you.