Presidents rarely tell us everything they know about the topic they are telling us about.

So it probably isn't shocking news to discover President Obama held back some key info that is no longer top secret in his Aug. 31 Oval Office address announcing the combat phase of the Iraq war had ended on schedule, as promised. Obama went on to talk about the urgent threat we still face from terrorists to explain why we must continue the fight in Afghanistan and Pakistan:

"And no challenge is more essential to our security than our fight against al-Qaida .... As we speak, al-Qaida continues to plot against us, and its leadership remains anchored in the border regions of Afghanistan and Pakistan. We will disrupt, dismantle and defeat al-Qaida, while preventing Afghanistan from again serving as a base for terrorists."

But the president's top intelligence analysts now believe the most severe threat to America's homeland today does not come from al-Qaida operatives based in Iraq, Afghanistan or Pakistan, but from a country he never mentioned in his 2,575 word speech:

Yemen.

Six days before Obama's address, The Washington Post reported this front-page news:

"For the first time since the Sept. 11, 2001, attacks, CIA analysts see one of al-Qaida's offshoots - rather than the core group now based in Pakistan - as the most urgent threat to U.S. security, officials said."

The new Number One threat comes from an al-Qaida affiliate in Yemen, the article said. Obama officials reportedly urged increased U.S. efforts there, including using armed CIA drones to launch so-called clandestine military strikes.

Now, U.S. presidents are not accustomed to droning on about the use of drones - those pilotless aircraft that are guided remotely to military strikes on terrorist sites within sovereign countries that have quietly, but never publicly, approved these attacks. It's all kept officially hush-hush even as it is officially ordered and journalistically reported as primetime/front-page news.

At times, since al-Qaida's 9/11 terror attacks, presidential rhetoric about an al-Qaida threat has been known to have exceeded reality (Remember the George W. Bush team's pre-Iraq invasion claim of a strong al-Qaida presence in Iraq?). Now, in his Aug. 31 references to challenges posed by al-Qaida strength in Iraq and Afghanistan, Obama may have bought himself a time-share in Bush's once-exclusive club.

In October 2009, Obama's national security adviser, Gen. James Jones, said, "The al-Qaida presence (in Afghanistan) is very diminished. The maximum estimate is less than 100 operating in the country, no bases, no ability to launch attacks on either us or our allies." In June 2010, CIA Director Leon Panetta told ABC News there were "at most" 50 to 100 al-Qaida operatives in Afghanistan.

Government intelligence analysts say a once-decimated Yemen-based offshoot of Osama bin Laden's al-Qaida - called "al-Qaida in the Arab Peninsula" (AQAP) - has gained strength and demonstrated intent to attack the United States. Previously, AQAP focused on its peninsula and neighboring Saudi Arabia; but an American-born Imam, Anwar al-Aulaqi, has assumed a leading role in AQAP. The Christmas Day 2009 near miss of an alleged AQAP suicide bomber on a Detroit-bound airliner prompted intelligence officials to jack up their threat assessment.

Intelligence analysts now believe offshoot groups such as AQAP or an al Qaida spinoff in Somalia - and not al-Qaida based in the Afghan-Pakistan border regions - is the likeliest source of future attacks on the West. Which means: Even eliminating al-Qaida safe-havens in Afghanistan and Pakistan will not eliminate threats to our homeland.

At the Combating Terrorism Center at the U. S. Military Academy at West Point, former FBI and CIA analyst Philip Mudd evaluated al Qaida's threat to the U.S. in last month's "CTC Sentinel." Mudd's assessment is candidly chilling. Suddenly it becomes understandable why his conclusion might not be shared with us by a president who, after all, seeks to lead but not panic:

"The United States will face attacks from affiliates and like-mindeds - the sheer volume of discrete plots makes a successful strike inevitable."

Martin Schram writes political analysis for Scripps Howard News Service.