There are two ways to move through the jungle - by boat or in a helicopter.
On foot is Jost not possible by more than a mile or two per day.
So the Vs would only really likely be able to attack along any Highways or along the coast.
A surprise attack is highly unlikely as crossing the boarder in force would be quickly swallowed up and give time for neighbouring nations (USA) the opportunity to apply a great deal of external pressure, even our own warship would be able to greatly hinder a costal hoping incursion.
In my past career, I was a Jungle Warfare Instructor and have served in this region, including training aircrew survival techniques. Much of the area along the coast is secondary jungle and almost impenetrable. A small defending force could hold up a larger army or poorly equipped troops indefinitely.
This is a political distraction technique.