The enemy has begun advancing under the cover of helicopters, and their speed is very fast.
One of the main characteristics of mountain warfare is that while you can see each other, you can't reach each other; to enter the range where you can inflict harm, you have to traverse mountains and ridges.
A straight-line distance of two kilometers means shooting is meaningless; this distance requires artillery, and the team taking the back route through the Three-leaf Jungle has already started to advance.
The people from the Three-leaf Jungle have also landed on the mountaintop. To attack, they have to descend the mountain and then climb up again, so even though they have been moving for twenty minutes, the distance hasn't closed much. On their way down, they can't proceed in a straight line; with the twists and turns, they have actually moved farther away.
