President Trump looks like he's trying catch those pesky pool vandals with some fancy new technology ... because new A.I. surveillance systems were just installed at the the Lincoln Memorial Reflecting Pool.

Our Charlie Cotton noticed these new A.I. security cameras being wheeled over to the Reflecting Pool on Monday -- the same day Trump claimed vandals carved a 300-foot long gash into the brand new Pool liner -- and when Charlie returned Tuesday, the surveillance systems were installed and running ... keeping a watchful eye over the Pool.

This is more than just an eye in the sky ... this A.I. features real-time tracking, intrusion detection, HD monitoring, strobe lights, automated spotlights and loud, talk-down horn speaker.

Trump's beefing up security through traditional measures too ... reinstalling fences and bringing in the National Guard and U.S. Marshals to patrol the area ... leading to multiple arrests.

As for those alleged, box-knife-wielding vandals Trump has been yapping about for a few days now ... well, back in May, Trump claimed the new Pool liner was so tough "if you had a knife you can't even cut it."

Now he's saying the opposite ... and most folks aren't even convinced there are vandals.

Also worth noting ... Google Maps says the Lincoln Memorial Reflecting Pool is "Temporarily closed." T

oo bad the ducks who live there can't Google that and save themselves from a toxic swim.