smugglers are wisening up, and throwing caltrops out behind them to keep Border Patrol from chasing them, a 2300 year old weapon, getting rediscovered and put back in use without any change in purpose or design

the caltrops have been used by smugglers on at least 20 different occasions in recent months, particularly in Otay Mesa, in an area just north of Tijuana International Airport, made from welding two bent nails together 

https://www-borderreport-com.cdn.ampproject.org/v/s/www.borderreport.com/immigration/border-crime/smugglers-toss-spikes-to-disable-border-patrol-vehicles-in-pursuit/amp