Analyse the changing nature of threats to peace and security since 1945, including nuclear weapons, terrorism, ethnic conflict and the international responses to them.

What this dot point is asking

You must explain how the nature of threats to peace and security changed across the period and assess how effectively the world responded. Strong answers connect different kinds of threat and weigh the strengths and limits of international action.

The nuclear threat and arms control

The atomic bombings of Hiroshima and Nagasaki (1945) opened the nuclear age and made the destruction of civilisation a real possibility. The Cold War arms race produced tens of thousands of warheads and the doctrine of mutually assured destruction. The Cuban Missile Crisis (1962) showed how close the world came to catastrophe. In response, states built an arms-control framework: the Partial Test Ban Treaty (1963), the Nuclear Non-Proliferation Treaty (1968), and the SALT and START agreements. Yet proliferation continued, with India, Pakistan, North Korea and others acquiring or pursuing weapons, keeping the nuclear threat alive after the Cold War.

Genocide, ethnic conflict and humanitarian intervention

The end of the Cold War unleashed long-suppressed ethnic and nationalist conflicts. The break-up of Yugoslavia produced wars and "ethnic cleansing", culminating in the Srebrenica massacre (1995) in which around 8,000 Bosnian Muslims were killed. In Rwanda, an estimated 800,000 people were murdered in the 1994 genocide while the world failed to intervene. These atrocities forced debate about a "responsibility to protect" and led to interventions, sometimes UN-led, sometimes by NATO, as in Kosovo (1999), and to the creation of international tribunals and the International Criminal Court (2002).

Terrorism and the post-2001 world

Terrorism became a defining security challenge, especially after the al-Qaeda attacks on the United States on 11 September 2001, which killed almost 3,000 people. The US-led "war on terror" produced the invasions of Afghanistan (2001) and Iraq (2003), the second of which was deeply controversial and launched without UN authorisation. Terrorism struck globally, including the Bali bombings (2002) that killed many Australians. These events raised hard questions about the balance between security and civil liberties, the legitimacy of pre-emptive war, and the effectiveness of military responses to a non-state threat.

International responses and historiography

The period saw a vast expansion of international machinery for peace and security: the United Nations and its peacekeeping missions, arms-control regimes, regional alliances such as NATO, and international courts. Their record is mixed. Peacekeeping succeeded in some places and failed disastrously in others, as in Rwanda and Srebrenica; arms control slowed but did not stop proliferation; and the war on terror arguably created as many problems as it solved.

Historians and analysts debate these issues: whether nuclear deterrence kept the peace or merely risked catastrophe; whether humanitarian intervention is genuine protection or great-power interest in disguise; and whether the post-2001 responses to terrorism were proportionate. SACE answers should weigh the changing threats against the strengths and limits of the international response.

Scholars and strategists disagree on how to read this record. Deterrence theorists argue that nuclear weapons paradoxically kept the great-power peace, since the certainty of mutual destruction made war irrational, while critics counter that the world survived by luck through crises such as Cuba and that proliferation makes deterrence ever more fragile. On humanitarian intervention, liberal internationalists defend the "responsibility to protect" as a moral advance, whereas realists and many in the Global South see it as a cloak for great-power interests, pointing to selective action. On terrorism, debate continues over whether military responses such as the Iraq invasion reduced or amplified the threat. A strong SACE answer holds these debates together, evaluating both the changing threats and the contested effectiveness of the responses.