AP United States History

## Learning Outcomes

- Explain how the **September 11, 2001** attacks changed U.S. foreign and domestic policy
- Distinguish clearly between the **Afghanistan War** and the **Iraq War**
- Identify the role of the **2001 AUMF** and the **2002 Iraq AUMF**
- Understand why both wars became prolonged conflicts rather than quick victories
- Analyze the tension between national security and civil liberties after 9/11
- Use specific evidence for SAQs, DBQs, and LEQs on post-Cold War U.S. foreign policy

## AP United States History Syllabus

For the AP United States History, you are expected to understand war on terror and prolonged conflicts, with a focus on the following syllabus points:

- Know that the **September 11 attacks** in **2001** led to a major shift in U.S. foreign policy and domestic security policy
- Identify the difference between the **2001 Authorization for Use of Military Force** and the **2002 Iraq AUMF**
- Explain why the United States invaded **Afghanistan in 2001** and **Iraq in 2003**
- Understand why the wars in Afghanistan and Iraq became long conflicts involving insurgency, occupation, and nation-building
- Identify major domestic responses including the **USA PATRIOT Act**, **TSA**, and the **Department of Homeland Security**
- Analyze debates over **civil liberties**, **surveillance**, **detention**, and executive power
- Understand that the War on Terror showed both the reach and the limits of U.S. military power in the 21st century

## Test Your Knowledge

_Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, look more closely at that area during your revision._

1. How did the **September 11, 2001** attacks change both U.S. foreign policy and domestic policy?
2. What is the difference between the **2001 AUMF** and the **2002 Iraq AUMF**?
3. Why did the wars in Afghanistan and Iraq become prolonged conflicts?
4. How did the War on Terror create tension between national security and civil liberties?
5. Name two Supreme Court cases that limited wartime executive power after 9/11.

## Introduction

The War on Terror is one of the defining developments of Period 9. For APUSH, it matters not only because of the attacks of **September 11, 2001**, but because it reshaped the presidency, military intervention, civil liberties, and public debate in the early 21st century.

A strong exam answer does more than say that the United States fought terrorism after 9/11. You need to show cause and effect. The attacks led to war in Afghanistan, then to war in Iraq, then to long occupations, public fatigue, and disputes over surveillance, detention, and the limits of executive power.

> **Key Term: War on Terror**
> The U.S. campaign launched after 9/11 to fight al-Qaeda and other terrorist threats through military action abroad and expanded security measures at home.

### 9/11 and the immediate U.S. response

The starting point is **September 11, 2001**. On that day, terrorists from **al-Qaeda** hijacked four planes. Two hit the **World Trade Center** in New York City, one hit the **Pentagon**, and a fourth crashed in Pennsylvania after passengers resisted. Nearly **3,000** people were killed.

The immediate political effect was unusual unity. Americans across party lines backed a strong response. This is an important distinction for APUSH: early support for intervention was broad, but that support weakened over time as the wars dragged on.

> **Key Term: September 11 attacks (9/11)**
> Terrorist attacks carried out by al-Qaeda on September 11, 2001, that killed nearly 3,000 people and transformed U.S. foreign and domestic policy.

Congress responded quickly by passing the **Authorization for Use of Military Force** on **September 18, 2001**.

> **Key Term: 2001 AUMF**
> A law passed after 9/11 authorizing the president to use force against those responsible for the attacks and those who harbored them.

This matters because it gave the president broad authority. It was aimed at those behind 9/11, especially **al-Qaeda** and the **Taliban** regime in Afghanistan that sheltered them. Over time, though, presidents used it far beyond the first invasion. That is one reason historians see the War on Terror as an expansion of executive war-making power.

At home, the government also built a larger security system. The **USA PATRIOT Act**, signed on **October 26, 2001**, expanded surveillance and information-sharing powers. The **Transportation Security Administration (TSA)** was created in **November 2001** to federalize airport security. The **Department of Homeland Security** was created by the **Homeland Security Act of 2002** and began operating in **2003**.

> **Key Term: USA PATRIOT Act**
> A 2001 law that expanded federal surveillance, intelligence-sharing, and law-enforcement powers in terrorism investigations.

These measures show a major APUSH theme: crisis often leads to expanded federal power. The same broad pattern appeared during the Civil War, World War I, World War II, and the Cold War. After 9/11, the pattern returned in a new form.

> **Test Tip:** If an SAQ asks how 9/11 changed the U.S., always give one foreign-policy effect and one domestic effect. For example: invasion of Afghanistan abroad, PATRIOT Act at home.

### Afghanistan: the direct response to 9/11

The war in **Afghanistan** began in **October 2001**. This was the clearest and most direct military response to 9/11 because the Taliban government had given shelter to al-Qaeda and **Osama bin Laden**.

At first, the war seemed successful. U.S. forces and allies removed the Taliban from formal power quickly. This early success can mislead students. On exams, do not stop with “the U.S. overthrew the Taliban.” The harder historical point is why that did not end the conflict.

The war became prolonged for several reasons.

First, defeating a regime is not the same as creating a stable state. The Taliban lost power in major cities, but they remained active in rural areas and regrouped.

Second, the war expanded from counterterrorism into **nation-building**. That meant the United States was not just targeting al-Qaeda. It was also trying to build durable political institutions, security forces, and a democratic government in Afghanistan. Those goals were much harder and slower than the initial military campaign.

> **Key Term: nation-building**
> The attempt to create or rebuild stable political institutions, security forces, and civil society in a country after conflict or regime change.

Third, geography and local politics mattered. Afghanistan’s terrain, regional divisions, and weak central authority made long-term control difficult. Even after **Osama bin Laden** was killed by U.S. forces in **Pakistan** on **May 2, 2011**, the broader war continued.

That is crucial for APUSH analysis. If the original goal was to strike those responsible for 9/11, bin Laden’s death might seem like closure. But the war lasted until the U.S. withdrawal in **2021**, and the Taliban returned to power. That outcome reveals the limits of U.S. military strength. The United States could remove a regime quickly, but it could not easily create a lasting political order.

Afghanistan thus became the **longest war in U.S. history**.

### Iraq: a separate war with separate justifications

A common mistake is to treat Iraq as if it were just the second stage of the same invasion. It was not. Iraq was a separate war, justified through a separate political argument and a separate congressional authorization.

Congress passed the **2002 Iraq AUMF** on **October 16, 2002**.

> **Key Term: 2002 Iraq AUMF**
> A law authorizing the president to use force against Iraq under Saddam Hussein’s regime.

The Iraq War began in **March 2003**. The Bush administration argued that **Saddam Hussein** posed a danger because of alleged **weapons of mass destruction**, violations of U.N. resolutions, and supposed links to terrorism. The textbook material also notes claims that Saddam had helped orchestrate 9/11, though those claims were dubious.

For APUSH, the key distinction is this: **Afghanistan followed directly from 9/11; Iraq did not**.

No major stockpiles of weapons of mass destruction were found. That failure damaged U.S. credibility. This became one of the most controversial parts of the war because it made many Americans question the evidence, motives, and planning behind the invasion.

At first, the military campaign moved quickly. U.S. troops captured **Baghdad**, Saddam’s regime collapsed, and Saddam himself later went into hiding. But the removal of the regime created a **power vacuum**.

> **Key Term: power vacuum**
> A situation in which the fall of an existing government leaves no strong authority in place, often leading to instability and conflict.

That power vacuum helps explain why Iraq became a prolonged conflict. Military victory in the opening invasion did not create political order. Instead, rival political, ethnic, and religious factions competed for control. Insurgency spread. Sectarian violence deepened. U.S. forces shifted from invasion to occupation and state reconstruction.

The **Abu Ghraib** prison abuse scandal, made public in **2004**, further damaged the U.S. position. It weakened American moral authority and intensified criticism of detention practices and occupation policy.

The **Iraq surge** of **2007** increased troop levels and improved short-term security in some areas, but it did not settle the deeper political divisions in Iraq. This is exactly the kind of complexity APUSH rewards. A policy may produce limited short-term results while still failing to solve the larger problem.

By **2011**, U.S. troops formally withdrew from Iraq. Yet the war’s effects lasted. Instability in Iraq later helped create conditions that contributed to the rise of **ISIS** in the region. So even though the main U.S. occupation ended, the consequences did not.

> **Test Tip:** In essays, compare Afghanistan and Iraq directly. A fast way to earn analysis points is: Afghanistan = response to al-Qaeda and Taliban after 9/11; Iraq = separate invasion based on WMD claims and Saddam’s regime.

### Civil liberties, detention, and the limits of executive power

The War on Terror was not only about combat overseas. It also changed law, rights, and political debate inside the United States.

The PATRIOT Act expanded government surveillance powers. Later controversies over **NSA surveillance**, especially after **Edward Snowden’s** 2013 revelations, deepened concern that anti-terror policy had weakened privacy protections.

Detention policy became another major issue. The **Guantánamo Bay detention camp** opened on **January 11, 2002** in Cuba and held suspected terrorists outside the normal criminal justice system.

> **Key Term: Guantánamo Bay detention camp**
> A U.S. detention facility in Cuba used to hold terrorism suspects, associated with indefinite detention and legal controversy over due process and habeas corpus.

The administration also used **military commissions** to try some detainees.

> **Key Term: military commissions**
> Special tribunals used by the U.S. government to try certain wartime detainees outside the ordinary civilian court system.

The biggest constitutional issue was whether the president could detain people indefinitely without ordinary judicial review. This led to several important Supreme Court cases:

- **Hamdi v. Rumsfeld (2004)** — U.S. citizens held as enemy combatants had the right to challenge detention.
- **Rasul v. Bush (2004)** — federal courts could hear habeas claims from Guantánamo detainees.
- **Hamdan v. Rumsfeld (2006)** — the military commissions, as then structured, were not properly authorized.
- **Boumediene v. Bush (2008)** — Guantánamo detainees had constitutional habeas corpus protections.

These cases matter because they show that wartime executive power was broad but not unlimited. The presidency expanded after 9/11, but the courts placed limits on that expansion.

This creates a strong continuity-and-change argument for APUSH. Continuity: in wartime, the government often expands power and restricts liberties. Change: in the War on Terror, the courts pushed back in notable ways, especially over detention and habeas corpus.

Another domestic effect was increased suspicion and discrimination aimed at Muslim, Arab, and Sikh communities. This is useful evidence if you want to connect the War on Terror to broader themes of American identity and social conflict.

### Why these conflicts matter for APUSH interpretation

The War on Terror belongs in a much larger U.S. history pattern. Even after the Cold War ended, the United States remained interventionist. The main enemy changed—from Soviet communism to Islamist terrorism—but the impulse to use military power abroad continued.

At the same time, the War on Terror exposed limits that earlier triumphalist thinking sometimes ignored. The United States could topple governments rapidly, yet it struggled to produce stable outcomes afterward. That was true in both Afghanistan and Iraq.

The subtopic also fits the APUSH themes of **America in the World** and **Politics and Power**. Abroad, the U.S. projected military force in the Middle East and South Asia. At home, the executive branch gained broader powers, Congress delegated authority through the AUMFs, and the courts tested constitutional limits.

For LEQ or DBQ writing, a strong argument would not say simply that the War on Terror expanded U.S. power. It should also say that those expansions produced costs: long wars, public fatigue, constitutional disputes, and controversy over the justification for Iraq.

## Key Point Checklist

_This article has covered the following key knowledge points:_

- The **September 11, 2001** attacks killed nearly 3,000 people and transformed U.S. foreign and domestic policy
- The **2001 AUMF** authorized force against those responsible for 9/11 and those who harbored them
- The United States invaded **Afghanistan in October 2001** because the Taliban sheltered al-Qaeda
- The Afghanistan War became prolonged because of insurgency, weak state-building, and shifting goals from counterterrorism to nation-building
- The **2002 Iraq AUMF** was separate from the 2001 authorization and was aimed at Iraq under Saddam Hussein
- The United States invaded **Iraq in March 2003** over claims including weapons of mass destruction and security threats
- No major WMD stockpiles were found in Iraq, damaging U.S. credibility
- The Iraq War became prolonged because of occupation, insurgency, sectarian conflict, and a power vacuum after Saddam’s fall
- Domestic responses to 9/11 included the **PATRIOT Act**, **TSA**, and the **Department of Homeland Security**
- **Guantánamo Bay** and military commissions sparked major civil-liberties debates
- Supreme Court cases such as **Hamdi**, **Rasul**, **Hamdan**, and **Boumediene** limited executive wartime power
- The War on Terror showed both continuity in U.S. interventionism and the limits of American military power in long conflicts

## Key Terms and Concepts

- War on Terror
- September 11 attacks (9/11)
- 2001 AUMF
- USA PATRIOT Act
- nation-building
- 2002 Iraq AUMF
- power vacuum
- Guantánamo Bay detention camp
- military commissions


Challenges of the 21st Century - War on terror and prolonged conflicts