Hmmm....
What is the East soldier waiting to do?
Are you meaning that the West soldiers are landing on the shore from a boat, and after they activate a trigger the East attacks them?...
If that's the case, you need to give the East soldiers a waypoint away from where the boat lands, and in the Condition field replace "true" with "wp1==1" without the quotes. That will make the group stop at that waypoint.
Then, in the On Activation field of your trigger, put "wp1=1" without the quotes, and the East will continue on their waypoint path to attack the boat.
Hope that's what you're asking for...