The 34-year-old submarine had gone through a refit and was “in perfect condition,” Macri told reporters at the Argentine navy headquarters.
“My commitment is with the truth,” he said, adding the tragedy “will require a serious, in-depth investigation that will yield certainty about what has happened.”
Argentina’s navy has been fiercely criticized for its handling of the operation since first reporting the submarine overdue at its Mar del Plata base on November 16.
The navy took several days to say that the San Juan had reported a problem with its batteries in its final communication on November 15.
Only on Thursday did the navy confirm there had been an explosion on board, which experts said was likely linked to the battery problem.
“Until we have the complete information, we do not have to look for the guilty, to look for those responsible. First we have to have certainty of what happened and why it happened,” said Macri.
The center-right leader spoke as the search for the San Juan shifted from rescue to recovery on Friday, after navy officials lost hope of finding alive any of the crew, which included the country’s first female submarine officer.
“We have to find the submarine at the bottom of the sea, the area is large, the environment hostile, and the search very difficult,” said Argentine navy spokesman Enrique Balbi.
Magistrate Marta Yanez has already begun preliminary investigations into the disaster.
She told reporters that unlike a plane, “the submarine does not have a black box. The black box is the submarine,” and it would have to be recovered before the causes of the explosion could be known.
Officially the navy has not declared the loss of the crew, but marine experts believe an explosion would have been catastrophic.
Brenda Salva, a friend of crew member Damian Tagliapietra, said she had been told by the commander of the Mar del Plata naval base: “They are all dead.”
The navy said one sailor escaped the tragedy because he disembarked the submarine at Ushuaia for another mission — and was replaced by someone else.
A second sailor, aged 26, had been ready to join the ill-fated sub but was exempted because he was finalizing the purchase of a house, the Clarin newspaper reported.
For the relatives of the crew, grief turned to anger by Friday.
“I want to tell Admiral Marcelo Srur that he is not in a position to be in charge of a force, and to the president (Mauricio Macri), to bring order,” said Maria Rosa Belcastro, mother of 38-year-old Lt. Fernando Villarreal.
Relatives have focused their anger on the condition of the three-decade-old sub, which had undergone a seven-year refit to extend its service, and the navy’s guardedness since the start of the search operation.
In his comments at the navy headquarters, Macri paid tribute to the “patriotism, heroism and bravery” of the San Juan’s crew.
“For all of them and their families, my greatest affection,” he said.
To the relatives of the missing submariners he said: “The pain is great but we are together, and we are going to travel this road all the way together.”
Argentine press reports on Friday said Macri’s center-right government was preparing to sack navy chief Srur as part of a purge of top brass in a country where the military is distrusted.
“The government is considering changing the leadership of the navy. They believe there was negligence in the disappearance of the ARA San Juan and criticize the handling of the situation,” the influential Clarin daily said.
Memories are still fresh in Argentina of the 1976-83 military dictatorship responsible for the disappearance of an estimated 30,000 people.
Sociologist Ricardo Rouvier said the submarine drama “encompasses the question of the role of the armed forces” in a country where they are now on the margins of power.
There is also the issue of possible negligence or disinterest by political forces toward investment in the military, Rouvier said.
Macri, however, chose Friday to pay tribute to the navy and the armed forces as a whole. “Because they are the ones who have a central responsibility in the life of this country, which is to take care of our country, to take care of all of us,” he said.
Depths plummet from 200 meters to more than 3,000 meters on the edge of the Argentine shelf, where the sound of the explosion was picked up by hydro-acoustic sensors used by the Nuclear Test-Ban Treaty Organization.
Experts say the sub would begin to break-up once below depths of around 600 meters.