WASHINGTON, March 18: The United States has raised its security alert level from “code yellow” to “code orange” on Monday night, less than hour after President George W. Bush indicated his willingness to invade Iraq to oust the Iraqi regime.

In Washington on Monday night, roads around the White House were closed.

With the declaration, high visibility security was stepped up at airports, ports and border crossings.

“The intelligence community believes that terrorists will attempt multiple attacks against US and coalition targets worldwide in the event of a US-led military campaign against (President) Saddam Hussein,” said Homeland Security Secretary Gov. Tom Ridge in a statement announcing the raised threat level.

The security operation, codenamed “Liberty Shield,” includes more patrols by coastguard vessels, more intense screening of people and goods at border crossings and increased flight restrictions over New York, Washington and other cities.

“Orange” is the second-highest level in the United States’ five-stage, colour-coded alert system. The country was last put at “orange” on Feb. 7 because of warnings of possible terror attacks during the Haj. No terror attacks took place and the threat level was lowered to “yellow” nearly three weeks later.