Air strikes against Syria are illegal under UN Charter and international law.

https://pursuit.unimelb.edu.au/articles/does-it-matter-that-strikes-against-syria-violate-international-law

The University of Melbourne states that the air strikes against Syria are illegal.

http://www.xinhuanet.com/english/2018-04/14/c_137110826.htm

The UN Chief is also alarmed by the air strikes against Syria.