Al-Zawahri appeared in a video posted to a jihadist website on January 22. In it, he dared Bush to send the entire U.S. army to Iraq.
"Bush raves in his latest speech [on January 10] and among his ravings was that he will be sending 20,000 of his troops to Iraq," al-Zawahri said. "So I ask him, why send 20,000 only -- why not send 50,000 or 100,000? Aren't you aware that the dogs of Iraq are pining for your troops' dead bodies? So send your entire army to be annihilated at the hands of the mujahideen to free the world from your evil and theirs, because Iraq, land of the caliphate and jihad, is able to bury 10 armies like yours, with Allah's help and power."
New Security Effort
The first wave of U.S. reinforcements for Baghdad began arriving over the last three days.
The 3,200 fresh troops are part of a total of some 17,000 Washington will make available to boost security in the capital.
Bush said on January 16 that he is convinced the troops can restore order.
"Things have changed," Bush said. "In other words, I am not putting troops into a situation where there haven't been enough changes to assure me that we can make progress."
The designated new U.S. commander in Iraq, David Petraeus, says the troops -- along with Iraqi Army units -- will clear neighborhoods of insurgents and militiamen.
The general, whose Senate confirmation hearing takes place in Washington today, says the U.S. troops will be deployed in the neighborhoods they protect.
Coping With Al-Sadr
That breaks from previous policies of keeping U.S. troops on big forward operating bases.
Signs are mounting that the Imam al-Mahdi Army of radical Shi'ite cleric Muqtada al-Sadr is a particular target.
The U.S. military announced its troops and Iraqi forces have captured more than 600 militiamen loyal to al-Sadr in the past six weeks.
In what could be a peace overture, al-Sadr on January 19 ordered his representatives in the Baghdad government to end a two-month boycott of parliament. His supporters demand U.S. troops leave Iraq.
However, the al-Mahdi Army retains control of several formerly mixed Sunni-Shi'ite neighborhoods where it has forced Sunni residents to leave.
Such activities, plus bombing attacks on Shi'ite neighborhoods by Sunni extremists including Al-Qaeda, are pushing Iraq into civil war.