Answer:
The sentence "Without a serious, carefully crafted strategy, Southeast Asian countries are unsure what to expect from Washington’s future presence in the region" means that Southeast Asian countries are concerned about what the United States will do in the region in the future, because the United States does not have a clear plan.
The word "unsure" means that they do not know what to expect. The phrase "future presence" means what the United States will do in the region in the future.