Combat engineers primarily supervise, serve or assist as a member of a team when they are tackling rough terrain in combat situations. They provide their expertise in areas such as mobility, countermobility, survivability and general engineering.

A lifetime ago, I was an Army combat engineer. Many of the troops that the current White House occupant has sent to the U.S.-Mexico border as part of a publicity stunt to gin up public hostility toward the so-called migrant “caravan” are combat engineer battalions. The job of a combat engineer is really quite simple .

Construct fighting positions, fixed/floating bridges, obstacles and defensive positions

Place and detonate explosives

Conduct operations that include route clearance of obstacles and rivers

Prepare and install firing systems for demolition and explosives

Detect mines visually or with mine detectors

The portion of that job I want to focus on in it the first bullet point under “Job Duties.” Specifically: Construct [...] obstacles and defensive positions.

x The Fake News is showing old footage of people climbing over our Ocean Area Fence. This is what it really looks like - no climbers anymore under our Administration! pic.twitter.com/CD4ltRePML Ã¢ÂÂ Donald J. Trump (@realDonaldTrump) November 19, 2018

In the tweet above, the current White House resident posts this photo of concertina wire along the border fence. That is what a combat engineer would build as an obstacle, and/or a defensive position. It is also completely ineffective as an obstacle and/or a defensive position.

The obvious reason why it is ineffective is that all you have to do is get your hands on a pair of wire cutters, and you are through. The not-so-obvious reasons why it is ineffective are not something the untrained eye would know to even look for.