NEW YORK: Treasury Secretary Timothy Geithner on Tuesday told a packed room of Wall Street dealers and bankers they could not look America in the eye and argue that financial regulation is fine as it is.

Geithner said the financial system was tragically fragile after experiencing the worst crisis since the 1930s, and the government must respond by adding new regulation as well as improving on current ones.

"It's a war of necessity, not a war of choice," he said at the Securities Industry and Financial Markets Association annual meeting in New York. "And it's a just war."