TMZ Studios has a new special, "TMZ Presents: Under Fire: The Trump Assassination Attempt," where we explore the many, stunning security failures that lead to the attempt on Trump's life at his fateful Butler, Pennsylvania rally.

Richard Staropoli, a top former Secret Service Special Agent, is strongly suggesting the women assigned to protect Trump that day should shoulder a lot of the blame.

The way Richard sees it ... the women here were assigned more for optics than merit, and he has a big problem with what happened after the shooter missed Trump's head.

The issue ... when SS agents stand Trump back up on stage, a good portion of the presidential candidate's body is exposed ... and Richard says it's because the female agents just aren't tall enough to shield Trump.

Cheryl Tyler, another former Secret Service Special Agent, is pushing back on Richard's assessment ... she says height has nothing to do with an agent's ability to protect the President, male or female.

For Cheryl, Richard's beef here just doesn't hold up under scrutiny ... she says she knows a lot of male agents who have been shorter than the president they were assigned to protect.

Fair, or not, this criticism is a big part of the conversation on the would-be Trump assassination ... and he didn't have as many women agents protecting him at the ensuing RNC.