International organizations and the search for peace

World History · Common Test for University Admissions · 7 min read · Updated: Oct 22, 2026

World History Inquiry E "Challenges of the Global World": The Formation of International Organizations and the Quest for Peace

Hello, everyone! In this chapter, we will learn how humankind, having experienced the immense devastation of the First and Second World Wars, attempted to rebuild the international order and create mechanisms to maintain peace.
You might be wondering, "What is the difference between the League of Nations and the United Nations?" or "The structure of the Cold War seems so confusing..." Don't worry at all! Once you grasp the key points of comparison and the broad historical flow, you will be able to tackle source-based questions and true/false questions on the Common Test with complete confidence. Let's break it down together step by step!

*Note: The other chapters in this section ("Economic Globalization and Correcting Disparities," "Advancement of Science and Technology and the Knowledge-Based Society," and "Inquiry into the Challenges of the Global World") will be covered in detail in their respective individual chapters.

---

1. Mechanisms for Maintaining Peace: What Is "Collective Security"?

In pre-modern international society, the mainstream approach was the balance of power, where specific countries formed alliances to balance each other's strength. However, this carried the danger that when allied nations came into conflict, it could escalate into a massive, global war (such as World War I).

To overcome this, a new mechanism called collective security was devised.

[Understand It with an Analogy!]
・Balance of Power: Imagine a school classroom where Group A and Group B each gather friends to face off against each other. Once a fight breaks out, it turns into an all-out brawl.
・Collective Security: The entire class agrees on a rule: "If anyone uses violence, everyone will unite to stop that person and impose penalties." Because a rule-breaker would make an enemy of everyone, this effectively deters aggression right from the start.

---

2. Comparison Between the League of Nations and the United Nations

A very common topic on the Common Test is the similarities and differences between the League of Nations (after WWI) and the United Nations (after WWII). Let's compare them carefully with a mental chart in mind.

(1) The League of Nations (Inaugurated after WWI)

・Purpose: As history's first full-scale international peace organization, it aimed at preventing war and promoting international cooperation.
・Voting Method: In principle, decisions in the Assembly and the Council required unanimity.
・Sanction Measures: Only economic sanctions could be imposed against aggressor states (regulations regarding military sanctions and military forces that the League could mobilize were inadequate).
・Weaknesses & Challenges: The United States did not participate, despite proposing it (due to isolationism, congressional approval could not be obtained); the Soviet Union was initially excluded (it joined later, but was eventually expelled); and major powers such as Japan, Germany, and Italy withdrew one after another, meaning it could not prevent World War II.

(2) The United Nations (Inaugurated after WWII)

・Purpose: Learning from the shortcomings of the League of Nations, it was established as a more effective peacekeeping organization.
・Voting Method: The Security Council introduced the unanimity of the major powers (a majority vote that includes the concurring votes of all five permanent members), while the General Assembly fundamentally operates by majority vote.
・Sanction Measures: Effective sanctions are possible, including not only economic sanctions but also military action.
・Key Feature: Major powers, including the United States and the Soviet Union, participated from the very beginning.

[Key Takeaways: League vs. UN Checklist]
・Similarity: Both are based on the ideal of "collective security" and aim to maintain world peace.
・Difference ① (Member States): The United States did not join the League, whereas both the US and the USSR participated in the UN from the start.
・Difference ② (Decision-Making): The League generally required "unanimity," making swift decisions difficult, whereas the UN adopted "majority voting" (with great power unanimity in the Security Council).
・Difference ③ (Sanction Measures): The League was limited to economic sanctions, while the UN also possesses military sanction measures.

[Common Mistake]
A classic trap question is: "The League of Nations was proposed by an American president, but the United States itself did not join." Be careful not to assume that "because a country proposed it, they must have joined!"

[Did You Know?]
The League of Nations' principle of "unanimity" was actually a democratic attempt to respect the sovereignty and opinions of smaller nations. However, because a decision could not be made if even a single nation objected, it was impossible to take swift and decisive action against acts of aggression. Learning from this historical failure, the UN switched to a majority voting system.

---

3. Trends During the Cold War: Peaceful Coexistence and Multipolarization

After World War II, the Cold War began, marked by severe confrontation between the capitalist bloc led by the United States and the socialist bloc led by the Soviet Union. Although a direct, large-scale war was avoided, the world remained in a state of high tension due to the nuclear arms race and proxy wars across the globe.

(1) The Quest for Peaceful Coexistence

Despite the intense tension of the Cold War, from the mid-1950s onward, a move toward peaceful coexistence emerged, where both blocs sought to coexist while avoiding direct conflict. This arose from the mutual realization that a nuclear war would lead to the total destruction of humankind.

(2) The Progress of Multipolarization

The global order, which had been divided between the two superpowers (the US and the USSR), gradually moved toward multipolarization.
・Newly independent nations in Asia and Africa emerged from colonial rule and asserted a non-aligned stance, refusing to join either the East or the West.
・Western Europe and Japan achieved economic recovery and growth, gaining a stronger voice in the international community.
・Disagreements and conflicts of interest also arose within both the socialist and capitalist camps.
As a result of these developments, the world transitioned into a structure that could no longer be driven solely by the "two superpowers."

---

4. The End of the Cold War and the Rise of Regional Conflicts

From the late 1980s to the early 1990s, through reforms in the Soviet Union and political upheavals in Eastern Europe, the Cold War came to an end. This marked the moment when the East-West confrontation that had overshadowed the world for so long finally vanished.

(1) New Challenges: The Outbreak of Regional Conflicts

Many expected that the end of the Cold War would bring complete peace to the world, but reality was not so simple.
Ethnic disputes, religious conflicts, and historical border rivalries, which had been suppressed under the intense pressure and framework of the US and USSR, erupted all at once in various regions, bringing numerous regional conflicts to the surface.

(2) New Roles and Challenges for International Organizations

During the Cold War, the United Nations was often unable to function as intended because the US and the USSR frequently exercised their veto power against each other.
After the Cold War ended, veto confrontations among the major powers decreased, and expectations grew for UN activities in preventing regional conflicts, mediation, and peacebuilding. However, it now faces new, complex dilemmas regarding to what extent and in what manner it should intervene in internal civil wars and humanitarian crises within sovereign states.

[Summary: Key Concepts of This Chapter]
1. Collective Security: A mechanism where all members unite to contain rule-breakers (aggressors).
2. League of Nations vs. United Nations: Keep the differences straight, including US participation, unanimity vs. majority vote, and the strength of sanction measures.
3. Peaceful Coexistence and Multipolarization: The easing of the bipolar confrontation and the diversification of the world through newly independent nations and regional integration.
4. End of the Cold War and Regional Conflicts: Following the resolution of the East-West divide, previously suppressed ethnic, religious, and regional tensions surfaced.

Quick check

Can you answer these now?

Open each question to check the key ideas from this chapter.

What is the key difference between the traditional balance of power and collective security?

While the balance of power relies on opposing alliances balancing each other's strength, collective security establishes a universal agreement where all participating nations unite to deter and sanction any aggressor.

What structural and membership weaknesses undermined the effectiveness of the League of Nations?

The League required unanimous voting, had no provisions for military sanctions, and suffered from the absence of major powers—notably the United States, which never joined, and the Soviet Union, which was initially excluded.

How did the United Nations improve upon the decision-making and sanction mechanisms of the League of Nations?

The United Nations adopted majority voting with great power unanimity in the Security Council, included military sanctions alongside economic measures, and ensured the initial membership of all major powers.

What motivated the shift toward peaceful coexistence between the capitalist and socialist blocs from the mid-1950s onward?

Both superpowers recognized that a direct nuclear confrontation would result in the mutual annihilation and total destruction of humankind.

Which historical factors drove the multipolarization of global politics away from the US-Soviet bipolar structure?

Multipolarization was driven by newly independent Asian and African nations pursuing non-alignment, the economic recovery of Western Europe and Japan, and internal divisions within both Cold War blocs.

Why did regional and ethnic conflicts increase following the collapse of the Cold War order?

Long-standing ethnic, religious, and territorial disputes that had been suppressed by the rigid discipline and oversight of the US-Soviet confrontation surfaced rapidly once that bipolar framework vanished.

How did the post-Cold War environment change the role and challenges of the United Nations?

With fewer great power veto standoffs, expectations for UN peacekeeping grew, yet the organization faced complex dilemmas regarding how to intervene in internal civil wars and domestic humanitarian crises.

Ready to test yourself?

Turn these notes into exam-style practice. Get unlimited AI questions on this topic with instant marking and explanations.

Practice This Topic

More World History chapters

* The content provided by thinka is generated by AI and may not always be accurate or up-to-date. Please use it as a supplementary resource and verify with official materials.

Put These Notes into Practice

Reading the notes is a great start. Now practice with unlimited AI-generated questions and get instant feedback. 100,000+ students are already improving their grades.

Start Practicing Now View Pricing

Done reading? Test yourself with AI practice questions

Practice This Topic Now