The tweet came just after the German Foreign Minister Annalena Baerbock had toured the African Union.
The expected tank deliveries come as Ukraine dismissed several senior officials as part of an anti-corruption drive.
Musk said he had been "cutting costs like crazy" at the platform he bought for $44 billion.
Guzman is only allowed outside three times a week to a small area where he "doesn't get the sun".
After major Ukrainian gains in the second half of 2022, the frontlines have largely been frozen in place.