WASHINGTON — The far right corner of General David Petraeus’s charts told the story behind his reluctance to predict additional troop cuts in Iraq later this year.

As the number of American forces in Iraq has come down in the past three months, the number of high-profile car bomb and suicide attacks, weekly security incidents, civilian casualties, and episodes of ethno-sectarian violence has gone up.

On some of the graphs laid out by General Petraeus during congressional hearings yesterday, the brightly colored lines and bars showed a sharp uptick while in others the increase was slight and gradual.

But as they mapped progress for more than two years, the charts underscored the conclusion that the dramatic decline in violence from last June through December relied in part on the roughly 30,000 extra American troops sent to Iraq. Now that those forces have begun to leave, the security improvements have largely stalled.

“We haven’t turned any corners, we haven’t seen any lights at the end of the tunnel,” General Petraeus bluntly told members of the Senate Armed Services Committee. “The champagne bottle has been pushed to the back of the refrigerator. And the progress, while real, is fragile and is reversible.”