Short version: CFK has had it with the intelligence services who have kept people in positions of authority who have been around since the military dictatorship of 1976-83 and whose commitment to democracy and the rule of law are questionable.
In particular, she expects to get some definitive answers on the AMIA terrorism case in 1994.
The Buenos Aires Herald reports in CFK announces plan to dissolve SI intelligence service 01/26/2015:
President Cristina Fernández de Kirchner has announced that a bill will be sent to Congress ordering the dissolution of the Intelligence Secretariat (SI), calling both parliamentary chambers to special sessions on February 1 to discuss the proposal.She presented the proposal in an address to the nation, her first since the death of Nisman, 26 de ENE. Envio al Congreso Ley de creación de Agencia Federal de Inteligencia. Cristina Kirchner. Casa Rosada 26.01.2015:
In its place, CFK asserted, a new Federal Intelligence Agency would be created. In the new structure, both the director and deputy director would have to be designated and passed by the Senate, she explained in a television broadcast transmitted across the nation this evening. ...
The head of state asserted that from the moment the  Memorandum of Understanding with Iran over the AMIA bombings in 1994 was signed, "you could see that the agreement was being bombarded from the SIDE [intelligence service]".
"From there even the most unlikely accusations against this President were intensified. They started to occur at a dizzying pace," she added, stating that the manoeuvre included "groups of prosecutors, groups of judges, anonymous accusers and journalists who spread them."
"This led me to the decision to remove agents that had been there since before the coming of democracy." [my emphasis]
Federico Poore also writes about the proposed intelligence reforms in Long-overdue reform faces key obstacles Buenos Aires Herald 01/27/2015:
It was Juan Domingo Perón who created the relatively small State Intelligence Coordination (CIDE), but dictators Pedro Aramburu — head of the “Revolución Libertadora,” the military government that overthrew Perón in 1955 — and Juan Carlos Onganía expanded its objectives and personnel, renaming it the State Intelligence Secretariat (creating the now-famous acronym SIDE), a structure that lasted until 2001.Poore also takes note of the ugly role at least part of the intelligence service played in the AMIA case:
Canelo, one of the country’s foremost experts on military issues, said the turning point was the 1976 coup d’état, after which the spy agency became one of the major limbs of the repressive regime led by Jorge Rafael Videla.
When democracy returned to the country and Raúl Alfonsín took office in 1983 there was an authoritarian character to much of the intelligence arm of the government.
The intelligence system during the conservative government of Peronist leader Carlos Menem was further damaged by the 1994 bombing of the AMIA Jewish community centre as the SIDE played a major role in the cover-up of the case, said Paula Litvachky, director of the justice and security area of the CELS human rights organization.Poore also comments on divisions within the Argentine intelligence community that have been very much a part of the public discussion the last two weeks since Nisman's charges against CFK:
Former car dealer Carlos Telleldín was illegally paid US$400,000 by former federal judge Juan José Galeano to provide a false statement to implicate Buenos Aires province policemen in the attack — money that came directly from the SIDE coffers.
“In the AMIA case this was pretty clear, when we note the relationship between special prosecutor Alberto Nisman and some areas of the Intelligence Secretariat. The very Judge (Rodolfo) Canicoba Corral talked about these ties,” Litvachky added.
The ADC expert [Ramiro Álvarez Ugarte of the Association for Civil Rights] brought up the issue of the internal intelligence rift, that not only includes veteran spy Antonio “Jaime” Stiusso, a high-ranking intelligence official who has outlasted all the administrations since the early 1970s — including 12 years of Kirchnerite governments.Cristina is a fighter. Faced with a major smear campaign that she believes, obviously with good reason, is being conducted with significant participation from rogue intelligence officials (and possibly former officials), she has counterattacked with a new proposal to clean up the Intelligence Secretariat (SI).
This battle also involves Army Chief César Milani, a former head of military intelligence, who’s reportedly more trusted by the president than the SI itself. It may also explain the intelligence shake-up of last December, when SI’s chief Héctor Icazuriaga and his number two, Francisco Larcher lost their positions.