The Chitauri Neural Link connected every member of the Chitauri Command Center, and had also a double function as a life support system. When Iron Man intercepted a nuclear missile launched to New York City under orders of the World Security Council and used it to destroy the Command Center, all Chitauri forces on Earth got instantaneously disabled, ending the invasion. The destruction of the Chitauri Command Center prevented the connection of the troops to another ship.
In the aftermath of the Battle of New York, Vanchat acquired one of these Chitauri Links, and stored it in a flat in Paris. Grant Ward was tasked by S.H.I.E.L.D. with the retrieval of the Neural Link and handed it over to Deputy Director Maria Hill.