It severely damaged the main support base for Syria's fight against the Islamic State in eastern Syria. The event will possibly lead to a much larger war.

On April 4 Syrian airplanes hit an al-Qaeda headquarter in Khan Sheikoun, Idleb governate. Idleb governate is under al-Qaeda control. After the air strike some chemical agent was released. The symptoms shown in videos from local aid stations point to a nerve-agent. The release probably killed between 50 and 90 people. It is unknown how the release happened.

It is unlikely that the Syrian government did this:

In 2013 the Syrian government had given up all its chemical weapons. UN inspectors verified this.

The target was militarily and strategically insignificant.

There was no immediate pressure on the Syrian military.

The international political atmosphere had recently turned positive for Syria.

Even if Syria had stashed away some last-resort weapon this would have been the totally wrong moment and totally wrong target for using it. Over the last six year of war the Syrian government army had followed a political and militarily logical path. It acted consistently. It did not act irrational. It is highly unlikely that it would have now take such an illogical step.