"Disguised".
A Soviet cargo ship with "ИВАН ЛЕНИНГРАД" written in huge white letters on the bow - I'm not sure whether it counts as "disguised".
More importantly, only Soviet troops are traveling in "disguised" cargo ships. Chinese don't bother even with that; their fleet strolls across the Pacific out in the open with adorable little ships and red flags.
Overall, NATO fleets are mysteriously trashed in the game. In the Pacific there "isn't much left of our Pacific fleet" to the point when Chinese ships can move around unimpeded. Even "disguised" Soviet ships are hardly a trick that can work for long, yet they continue on unimpeded as well. In Atlantic, Soviet ships support attacks on US East coast. With vital sea lanes either dominated or completely under Soviet control, any US war effort in Eurasia is doomed.
Even US ground troops are depleted. The general in charge has two options to retake Seattle - either Sawyer's couple of battered battalions, or pulling troops from Europe. Let this sink in: Sawyer or Europe. CONUS is stripped bare of any combat-ready troops. It's Sawyer from the sea to shining sea. No reserves, no National Guard, no troops in training.
With this in mind, Parker's heroics in Southern France and Seattle have bought NATO leadership a (very uncomfortable) place at negotiating table as opposed to unconditional surrender. By the end of the game, NATO needs a miracle to win a war without reserves and control over seas.