Chapter 5 of Army Field Manual 3-0 Operations discusses the U.S. Panamanian invasion entitled Operation Just Cause. The manual details what occurred on December 19, 1989 and December 20, 1989. It does not discuss how President Bush and the U.S. Army began preparations in May, 1989.
The 193rd Infantry Brigade was the main combat unit stationed near Panama City, Panama. This brigade conducted training exercises code-named Aca,!A"Sand FleaAca,!A?. This included military operations on urban terrain (MOUT) training and live-fire exercises. Makeshift buildings were constructed for the MOUT training. These training exercises were frequently conducted. Therefore, Panamanian Defense Forces (PDF) became desensitized to U.S. troop’s movements. This assured Operation Just Cause would remain a surprise.
What types of training exercises is the U.S. conducting today? More importantly, why is the U.S. conducting certain exercises? The U.S. participated in Eager Lion, which was a joint Middle East exercise with 28 nations in 2019. Participants primarily included NATO and Middle East Allies. It consisted of theater movements on land, sea, air, and simulated electronic and cyber threats. This exercise in Jordan was the largest Middle East military exercise to date and consisted of nearly 8,000 individuals. Notable U.S. groups included the Army’s 4th Infantry Division, U.S. Marines with India Company, and a landing from the U.S. Navy USS Boxer. Additionally, U.S. Special Operations Forces participated in Eager Lion in August and September.
Escalating U.S. and Iranian tensions has made many wonder if additional hostilities will arise. China, Russia, and Iran recently held joint naval exercises in the Gulf of Oman. Only time will tell if these joint exercises are part of a larger strategic operation.
Sources:
https://www.army.mil/article/14302/operation_just_cause_the_invasion_of_panama_december_1989
https://www.armytimes.com/news/your-army/2019/10/09/largest-middle-east-military-exercise-features-army-marine-ground-troops-in-multi-domain-and-urban-defense/