Reclaimed States of America

In the 23th Century, The Earth enter into advance state. Due to Humans and Other species fighting each other have ended. The Reclaimed States of America have became the Hydro-Superpower around the world thanks to the alien technology and blood dragon tech since the 1980s and 2000s

After colonizing planets and taking resources. Anything was peaceful, Until it was shattered when the gate suddenly appeared in the washington dc when the roman like army attack and taken many slaves. But they're repelled by the Military. The RSA Send the army to the otherside. But they're met with JSDF on alnus hill. How will the JSDF and RSA React to this?