The Obama administration is expected as soon as this week to authorize the sale of two guided missile frigates to Taiwan, U.S. congressional sources said Monday, in spite of China's opposition to the deal.

"We're expecting an announcement as early as this week," a Republican congressional aide said. Another congressional aide said the notification from the administration is expected "any time now."

The sale will mark the first time in four years that the United States has shipped arms to Taiwan, the longest gap in such arms sales in nearly four decades.