There's nothing particularly unusual in that, since these silicon steel cities are supposed to build themselves. But when the city starts to kill everything around, then something has to be done about it.
Whether it's the waves crashing on to its circuits or perhaps a radiation storm, Xarq has swapped to planet-cleansing mode and has started to build up the necessary power in its central reactor to do the job. Somebody has to fight their way through the Zimmerman trenches that surround Xarq and shut down the reactor. That somebody is you.
As you approach the mass of silicon and steel in your Hydraboat armed with lasers mortars, guided missiles and depth charges, you suddenly come under attack. Fight your way through the planes, submarines and land-based guns taking pot-shots at you and you may figure out which parts of Xarq are worth hitting and which are just decoration.
Knock out laser field generators and the deadly laser barriers will collapse, pumping and repair stations will weaken the complex but the power field generators are your real targets. Lose these and you are in with a chance.
The trenches are arranged in levels around the reactor and you will have to battle through each one in turn until you can blast the lock gates to flood the next to allow your boat to pass.
You can also make use of the repair stations that will patch up your boat, but beware these are usually heavily guarded and you may come out of one in a worse shape than when you went in.