Gate: War in Runeterra

In June 2019, a strange structure appears in the center of Los Angeles, from which an unknown army begins its attack. This continued until the US national Guard arrived. After a couple of weeks, the government decides to send its troops through the gate to another world, which would calculate the attackers, explore the world and establish friendly relations. But how will the local population and other countries react to a new army that can destroy their world at the touch of a button?