The subject does not match the article content.

"Israel warns of possible pre-emptive chemical weapons strike in Syria" means that Israel is warning that they may conduct an attack on Syria and that Israel might use chemical weapons to make the strike.

However, to reflect the actual article content, the headline should read "Israel warns of possible pre-emptive strike on chemical weapons in Syria."

Big difference in meaning. Yes. Sometimes even I grow tired of sloppy English grammar, especially when it profoundly changes the meaning of what is truly being expressed.

Thread: Does anyone in MSM still know English?