After the second Brotherhood of the Evil Mutants tried to assassinate Senator Robert Kelly while he was performing a public research on the possible threat of superhuman beings and mutants, the President's Cabinet authorized secret and illegal Project Wideawake to research and, if needed, capture any superhuman mutant that the Project management could consider a threat to national security. The Project's head was Henry Peter Gyrich, answering only to the President, with Senator Kelly himself as an special consultant.
The government contacted industrial tycoon Sebastian Shaw, ignoring that Shaw was a evil mutant himself, to build the new breed of Sentinels. Shaw Industries is authorized by the government to build top-secret Sentinels to be used in Project Awakening.
Shaw produced three models: Mark IV Sentinels, Mark V Sentinels and Mark VI Sentinels. None of these models proved to be as formidable as the Mark II Sentinels. The models were constantly being modified and improved. Shaw secretly used Sentinels to attack his own enemies, the X-Men, but the government was unaware of this.
Cables: The Mark IV could attack with cables from their wrists.
Energy Blast: The Mark IV had an amount of different blasts, including but not limited to plasma, electrons, stunning gas and heat, that could be shot from their palms and eyes. They were also armed with a disintegrator that only worked with inorganic matter.
Flight using jets built into their feet.
Learning Program: A special learning program allowed a particular Mk IV a certain advantage when fighting an enemy, but only after at least one minute of analysis. This data could be stored for future uses against the same enemy, so that any Sentinel from any model could access the information (and Shaw or the government could authorize the development of special weaponry). However, any needed modification would take at least one week.
Mutant Detection: The Sentinels constantly scanned all the living beings in the immediate surrounding area and were able to determine if they were humans or mutants.
Robot: Due to its nature, the sentinels were protected by the sheer strength of the hull. They could not be affected by emotional or mental attacks, nor by illusions. However, they were susceptible to attacks affecting machinery.
Searching Lights: This model's eyes were equipped with searching lights.