The discovery of the wreckage of an Argentine submarine lost a year ago has revived a stalled probe into the cause of the undersea disaster that took the lives of 44 crew members.
Families of the victims have called for the ARA San Juan to be refloated, an enormous undertaking that authorities cautioned was likely beyond their means.
"We're talking about a vessel that, filled with water, weighs 2,500 tons," said the judge in charge of the investigation, Marta Yanez.
Yanez said she would not risk raising the submarine "if that means causing it to break up."
"But at the same time we know where they are and it is the first step to learn the truth of what happened."
In a message, Macri promised to get to "the truth needed to honor and respect our heroes and their families."