President Obama Honors Argentine Victims of 'Dirty War'

The president visited a memorial to the 1976 military coup.

—BUENOS AIRES, Argentina -- President Obama paid tribute to the victims of Argentina’s so-called “Dirty War,” honoring thousands of Argentinians killed by visiting the Parque de la Memoria on the 40th anniversary of the 1976 military coup, acknowledging “controversy about the policies of the United States early in those dark days.”

"I believe we have a responsibility to confront the past with honesty and transparency,” Obama said. “A memorial like this speaks to the responsibilities that all of us have. We cannot forget the past, but when we find the courage to confront it, and we find the courage to change that past, that's when we build a better future."

Walking alongside Argentine President Mauricio Macri through the memorial, the leaders reached the inscription of Fernando Brodsky, where they were met by Fernando's brother Marcelo Brodsky. The trio continued through the memorial, pausing at the name of Toni Motta -- an American journalist who disappeared during the violence.

The presidents were handed small bouquets of white roses and walked onto a pier, where they tossed the flowers into the river where many of the victims were drowned.

Obama said the United States government would declassify U.S. military and intelligence documents related to the "Dirty War," at the request of Macri and human rights groups.

ABC News' Ben Siegel contributed to this report.