Katie Holmes and Tom Cruise went from zero to nuclear war in an instant when she filed divorce papers, but it was little Suri who became the peacemaker ... sources familiar with the situation tell TMZ.
Our sources say ... a week ago Thursday, after Katie filed, the hostility between the two was palpable and Suri became a weapon. Katie wanted to strip Tom of all decision-making power in Suri's life, and Tom responded by unleashing the biggest legal guns around to fight her.
We're told what turned everything around was a series of conversations that Suri would be irreparably damaged by parental warfare. It registered big time with both Tom and Katie, and it allowed their lawyers to strike a deal in what could be record time for this type of divorce.
Fact is ... it generally takes celebs in these high-profile divorces a lot longer to realize how bitterness affects small kids, so credit to both.