POLICY Viewing the War as a Lesson to the World By DAVID E. SANGER WASHINGTON, April 5 — Shortly after Defense Secretary Donald H. Rumsfeld issued a stark warning to Iran and Syria last week, declaring that any "hostile acts" they committed on behalf of Iraq might prompt severe consequences, one of President Bush's closest aides stepped into the Oval Office to warn him that his unpredictable defense secretary had just raised the specter of a broader confrontation. Mr. Bush smiled a moment at the latest example of Mr. Rumsfeld's brazenness, recalled the aide. Then he said one word —...