Consider the following premises. For all y, if y were a soldier, then y is poor. There is at least one y for which if y were a soldier, then y is poor. For all y, if y were poor, then y is a soldier. Can we infer the following from them? If we can, name the inference rule being used: For all y, if is not true that y is a soldier if and only if y is poor.
That contradicts the premises. Therefore the answer is no.