Timeline of Events - September 11, 2001
American Airlines Flight 11 strikes the North Tower of the World Trade Center
United Airlines Flight 175 strikes the South Tower of the World Trade Center
American Airlines Flight 77 strikes the Pentagon
FAA grounds all civilian aircraft in US airspace - first time in history
Confirmed records indicate DEFCON 3 ordered by Secretary of Defense Donald Rumsfeld
United Airlines Flight 93 crashes in Pennsylvania after passenger uprising
DEFCON Response
Why DEFCON 3?
Confirmed records suggest the decision to raise DEFCON to level 3 was made for several reasons:
- Unknown Scope: The full extent of the attack was unknown - more attacks could be imminent
- State Actor Uncertainty: Initial uncertainty whether attacks involved a nation-state
- Continuity of Government: Need to protect national command authority
- Force Protection: Ensuring military installations were protected
Why Not DEFCON 2 or 1?
Confirmed records suggest DEFCON 2 and 1 are reserved for nuclear war scenarios:
- No nuclear threat was identified
- No nation-state attack requiring nuclear response
- DEFCON 3 provided appropriate readiness for conventional response
Military Actions Taken
Immediate Response
Confirmed records indicate the immediate response included:
- Fighter Scramble: F-15 and F-16 fighters scrambled from multiple bases
- Combat Air Patrols: Continuous armed patrols over major cities
- Nuclear Forces: Strategic nuclear forces at heightened alert
- NORAD: North American Aerospace Defense Command at full readiness
- All Military Bases: Enhanced security posture implemented
Operation Noble Eagle
The ongoing homeland defense operation that began on 9/11, as described in confirmed records:
- Continuous combat air patrols over US cities
- Enhanced air defense radar coverage
- Coordination with FAA for airspace security
- Continues in modified form according to confirmed records
NATO Response - Article 5 Invocation
Historic First
On September 12, 2001, NATO invoked Article 5 (collective defense) for the first and only time in the alliance's history. An attack on one member is considered an attack on all.
NATO Actions
- AWACS aircraft deployed to patrol US airspace
- Standing Naval Force Mediterranean deployed to Eastern Mediterranean
- Enhanced intelligence sharing
- Foundation for Operation Enduring Freedom (Afghanistan)
Aftermath and Return to Normal
DEFCON Reduction Timeline
- September 14: Initial lowering of DEFCON level begins
- Following Weeks: Gradual reduction as threat assessed
- Specific Levels: Exact timeline remains classified
Long-Term Changes
9/11 fundamentally changed US defense posture:
- Creation of Department of Homeland Security
- Enhanced domestic surveillance capabilities
- Permanent combat air patrols capability
- Revised threat assessment procedures
Historical Record
Date: September 11, 2001
Level: DEFCON 3
Significance: First DEFCON 3 since 1973; ordered during the 9/11 attacks.
Frequently Asked Questions
What DEFCON level was the US at on September 11, 2001?
The United States raised its defense condition to DEFCON 3 on September 11, 2001. This was ordered by Secretary of Defense Donald Rumsfeld approximately 10:00 AM Eastern Time, as the attacks were still unfolding.
Was 9/11 the highest DEFCON level ever reached?
No. DEFCON 2 was reached during the Cuban Missile Crisis (1962) and Operation Desert Storm (1991). DEFCON 3 on 9/11 was, however, the highest level reached since the 1973 Yom Kippur War and the first elevation since the end of the Cold War.
Why wasn't DEFCON 1 declared on 9/11?
DEFCON 1 is specifically for nuclear war scenarios where nuclear conflict is imminent or underway. The 9/11 attacks, while devastating, were not a nuclear threat and did not involve a nation-state adversary requiring nuclear response. DEFCON 3 provided appropriate military readiness for the situation.