yahoo.dk is Denmark. No US soldier would have a Denmark address. That's really quite amateur phishing.

Most phishers are well insulated by layers of protection. IP proxies burying their own and often key data keyed in at public computers in libraries or more often internet cafes. One would have to subpoena the server logs of Yahoo.dk to see which IP set up the account and trace it from there. Then one would have to hope the internet cafe, library has records of who was occupying their computers at the given time.

In a film there would be a security camera watching the computer in question and the bad guy would be revealed in two minutes of intense covert searching.

In the real world you have somewhere around a 1 in 500,000 chance of catching the perp. And then only if he/she is really dumb. The cost to try and catch the perp is more than the gain. The perps count on this as they commit their cyber-crimes.