Nearly everybody has heard of the United Nations. But how many know what it actually does? Or how it works? Or why, as world leaders gather for the 73rd session of the United Nations General Assembly, the institution has struggled to live up to the promise of its founders: making the world a better, more peaceful place?
The United Nations Charter was signed at a conference in San Francisco in June 1945, led by four countries: Britain, China, the Soviet Union and the United States.
When the Charter went into effect on Oct. 24 of that year, a global war had just ended. Much of Africa and Asia was still ruled by colonial powers.
After fierce negotiations, 50 nations agreed to a Charter that begins, “We the peoples of the United Nations.”
Why is that opening line notable? Because today, the United Nations can, to some, seem to serve the narrow national interests of its 193 member countries — especially the most powerful ones — and not ordinary citizens.
These parochial priorities can stand in the way of fulfilling the first two pledges of the Charter: to end “the scourge of war” and to regain “faith in fundamental human rights.”
In 1948, the United Nations proclaimed the Universal Declaration of Human Rights. These include the right to not be enslaved, the right to free expression, and the right to seek from other countries asylum from persecution.
However, many of the rights expressed — to education, to equal pay for equal work, to nationality — remain unrealized.
Each fall, the opening session of the United Nations General Assembly becomes the stage where presidents and prime ministers give speeches that can be soaring or clichéd — or they can deliver long, incoherent tirades, such as the one given by Col. Muammar el-Qaddafi, the Libyan strongman, in 2009. In 2017, President Trump threatened acts of aggression against rival nations, vowing to “totally destroy” North Korea if it threatened the United States or its allies.
The event offers plenty of star power, but critics contend that it is little more than a glorified gabfest.
For the rest of the session, the General Assembly is the arena where largely symbolic diplomatic jousts are won and lost. Hundreds of resolutions are introduced annually. While some of them earn a great deal of attention — like one in 1975 that equated Zionism with racism — they are not legally binding. (The Assembly is responsible for making some budgetary decisions.)
In principle, nations small and large, rich and poor, have equal voice in the Assembly, with each country getting one vote. But the genuine power resides elsewhere.
The 15-member Security Council is by far the most powerful arm of the United Nations. It can impose sanctions, as it did against Iran over its nuclear program, and authorize military intervention, as it did against Libya in 2011.
Critics say it is also the most anachronistic part of the organization. Its five permanent members are the victors of World War II: Britain, China, France, Russia and the United States. The other 10 members are elected for two-year terms, with seats set aside for different regions of the world.
Efforts to expand the permanent membership of the Council to include powers that have emerged since 1945 — such as India, Japan and Germany — have been stymied. For every country that vies for a seat, rivals seek to block it.
Any member of the permanent five — or the P5, for short — can veto any measure, and each has regularly used this power to protect either itself or allies. Since 1990, the United States has cast a veto on Council resolutions 18 times, many concerning Israeli-Palestinian relations. Russia has done so 22 times in that period.
The Charter does allow the General Assembly to act if, because of a veto, international peace and security are threatened. But in reality, that is rarely done.
The Security Council’s job is to maintain international peace. Its ability to do so has been severely constrained in recent years, in large part because of bitter divisions between Russia and the West.
The Council has been feckless in the face of major conflicts, particularly those in which permanent members have a stake.
Most recently, its starkest failure has been the handling of the seven-year conflict in Syria, with Russia backing the government of President Bashar al-Assad, and the United States, Britain and France supporting some opposition groups. The Security Council has failed to take decisive action on Syria, despite reports of countless war crimes.
It also failed to halt the fighting in Yemen, despite a disastrous humanitarian situation, including a cholera outbreak, and reports from its own investigators of war crimes on both sides. Last year, the Council was confronted with wide-scale atrocities against the Rohingya ethnic group in Myanmar, but has done little in response.
North Korea, an ally of China, has also consistently defied the United Nations, ignoring prohibitions against its nuclear program and missile tests. And the global body has had little sway in the seesawing diplomacy between Washington and Pyongyang, which has swung from threats of military strikes to the groundbreaking meeting in June between President Trump and Kim Jong-un, the North’s leader.
The Charter is vague in defining the duties of the secretary general, the United Nations’ top official. He or she is expected to show no favoritism to any particular country, but the office is largely dependent on the funding and the good will of the most powerful nations.
The Security Council — notably the P5 — chooses the secretary general, by secret ballot, to serve a maximum of two five-year terms. This process makes it difficult for the role to be independent of the P5’s influence.
The secretary general has no army to deploy, but what the position does enjoy is a bully pulpit. If the officeholder is perceived as being independent, he or she is often the only person in the world who can call warring parties to the peace table.
The current secretary general, António Guterres, a Portuguese politician, took the reins last year. He was the United Nations High Commissioner for Refugees from June 2005 to December 2015.
The actions of his predecessor, Ban Ki-moon of South Korea, repeatedly displayed the limits of the office’s authority during his 10-year tenure. For example, Mr. Ban was persuaded for two years in a row to keep powerful countries off a list of those whose military forces had killed and maimed children.
Since 1946, nine people have held the position of secretary general. All have been men.
When Mr. Guterres took on the role of secretary general, he inherited a body facing the unenviable task of demonstrating the United Nations’ relevance in a world confronting challenges that were inconceivable 73 years ago.
Here are some of the questions that will determine whether the organization’s influence diminishes or grows:
■ Can the Security Council take action against countries that flout international humanitarian law? And can the P5 countries look beyond their own narrow interests and rivalries to find ways to end the “scourge of war”?
■ Can peacekeeping operations be repaired so that the protection of civilians is ensured?
■ Can the United Nations persuade countries to come up with ways to handle the new reality of mass migration?
■ Can the secretary general persuade countries to keep their promise to curb carbon emissions — and to help those suffering from the consequences of climate change?
■ Can the United Nations get closer to achieving its founding mandate, to make the world a better, more peaceful place?
An earlier version of this article first ran on Sept. 16, 2016.