The orbital drop of the Decepticons was precise and swift, and no country on Earth managed to figure out where they were coming from.
But just as Lille predicted: the Decepticons were on the defensive.
When a criminal holds hostages, even if the police could bring in a hundred tanks, it's impossible to unleash such firepower indiscriminately.
In the past, the Decepticons always had the upper hand, either hiding within human society or obtaining information ahead of humans, running circles around the Autobots and humanity. Most of the successes of the NEST force were from catching a few hidden Decepticons, and Megatron may not even know what tasks to assign them.
This time was different: there's a device on Earth capable of detonating the Sun Harvesting Energy — something the Autobots would never use, but the Decepticons would see as their last hope for reviving Cybertron.