The estimate includes 124 military, civilian and contractor employees who were working in the Pentagon at the time of the crash and 64 passengers aboard the aircraft, including five hijackers.
Among those employees believed to have perished in the attack, 74 were affiliated with the Army, 42 with the Navy, and eight were employed by Defense agencies. Two other Defense agency employees were also presumed dead--one was aboard the jet that crashed into the Pentagon and the other was aboard United Flight 175, one of two hijacked flights that crashed into the World Trade Center twin towers in lower Manhattan the same morning.
While the recovery operation continues, Defense officials are gearing up for what senior Bush administration officials are calling a prolonged war against terrorism.
In an interview with reporters Sunday morning, Defense Secretary Donald Rumsfeld said, "It will take a broad, sustained effort that will [require] our diplomatic, our political, our economic, our financial strength as well as our military strength, and unquestionably unconventional techniques. And it will take time. It's not a matter of days or weeks. It's years."
Rumsfeld said fighter aircraft at some 26 bases around the country are on "strip alert," meaning they can be mobilized on 10 to 15 minutes notice. Military forces are also on a very high state of alert.
"The reality is that a terrorist can attack at any time in any place using any technique, and it is physically impossible for a free people to try to defend in every place at every time against every technique," Rumsfeld said. "What does that mean? It means that the President is exactly right, that we have to take this battle, this war, to the terrorists, where they are. And the best defense is an effective offense, in this case. And that means they have to be rooted out."
On Friday, Bush authorized the call-up of as many as 50,000 National Guard and Reserve personnel to active duty. The call-up would augment thousands of reservists who already have returned to active duty voluntarily since Tuesday, Defense officials said.
Service officials are estimating they will need about 35,000 reservists very soon: 10,000 soldiers, 13,000 airmen, 3,000 sailors, 7,500 Marines and 2,000 Coast Guardsmen. Individual reservists and reserve units could be called up involuntarily at any time, said Craig Duehring, assistant secretary of Defense for reserve affairs.
"The kind of units that might be called up include air defense, airlift, intelligence support, military police, medical, logistics, engineers, search and rescue, civil affairs, chaplains and so forth," said Duehring.
The last time the ready reserve underwent a partial mobilization, as this call-up represents, was in January 1991, before the Persian Gulf War.
While many of the reservists called up are expected to be deployed in support of recovery operations in New York City, many others will be employed in more typical warfighting missions, such as defending the air space around major metropolitan areas and filling in for active-duty personnel who may deploy overseas, Defense officials said.
In an interview with the PBS "Newshour" on Friday, Deputy Defense Secretary Paul Wolfowitz said the administration assumes that more terrorists remain in the country.
"We have to operate on the assumption that we haven't seen the end of this kind of terrorism. But we also have [to] understand that what we saw on Tuesday completely transforms the problem. We've got to think anew about this," Wolfowitz said.
"The policies of the last 20 years--whether you think they were carried out effectively or ineffectively--obviously don't work. This is not going to be a problem solved by locking somebody up and putting them in jail. It's not going to be solved by some limited military action. It's going to take…a broad and sustained campaign against the terrorist networks and the states that support those terrorist networks," he said.
Wolfowitz added, "Given some of the weapons … these terrorists are after, what we saw on Sept. 11 could be just the beginning."