Breen has served as interim CEO since Ellen Kullman stepped down in October. He has been on the board of DuPont (DD) since February of this year, and before that served for 10 years as chief of Tyco International (TYI), a security systems company. Before becoming CEO of Tyco, Breen held several management positions at Motorola (MDI) and led the now-defunct General Instrument Corporation.

Breen’s appointment increases the likelihood that the 213-year-old conglomerate will be broken up. According to Bloomberg, Breen has already discussed deals involving DuPont’s seed and crop-chemicals unit, the company’s largest segment by revenue. Moreover, as the Wall Street Journal noted when Breen was appointed to the post of interim CEO, he is known as a “breakup expert”: He split Tyco twice during his tenure as CEO.

A DuPont breakup is exactly what Kullman, No. 5 on Fortune‘s list of the Most Powerful Women, fought so hard to prevent while she held the top job. She took on activist investor Nelson Peltz, who wanted to split DuPont into parts, ultimately winning a proxy battle and preventing Peltz’s hedge fund, Trian Fund Management, from gaining seats on her company’s board.

When Kullman announced her retirement, there was much speculation as to whether she really won the activist war. Fortune editor Alan Murray argued that her abrupt departure signaled a loss, while Fortune senior editor Stephen Gandel wrote that Kullman left on her own terms and wasn’t pushed out by Peltz. If Breen does indeed dismantle the company Kullman went to such lengths to keep intact, it will become much harder to argue that Kullman emerged from that fight the victor.