Sudan is a pathetic country, extremely corrupt, poor, and weak, its army probably consists of conscripted spearchuckers firing AK47s from donated rescue helicopters. The Russians would probably arm them, but there are not enough trained Sudanese to put up impressive resistance, and besides, the extent of Sudan is vast and the small army cannot defend it. Sudan is a huge country with a long coastline, enormous oil reserves, fertile land, etc. and it was historically a territory of Egypt.