The War Powers Act comes into play here. The president has 48 hours to notify Congress and can commit for up to 60 days. Multiple outlets reported Congress was notified, as was Russia, as was Israel, and countries including Canada support the strikes. So it seems to me that word circulated around as necessary.
What's interesting to me isn't a strike on an airfield, it's that the strike happened while the Chinese PM was at dinner with Trump. The timing was intentional. Wonder if Kim-Jong Un will be performing a surprise, extended subway inspection tour…