What Is the United Nations General Assembly?

— -- Amidst a weekend filled with terror that rocked major cities in New York and New Jersey, the world’s most powerful leaders have assembled to tackle the globe’s most pressing issues, including national security, climate change, nuclear proliferation and the refugee crisis.

The gathering -- the United Nations General Assembly -- will see more than 140 heads of state and delegations converge in New York City.

What Is the United Nations General Assembly?

The United Nations General Assembly, or UNGA, is one of the six principal structures of the United Nations, an intergovernmental organization with 193 members made up of sovereign states that promotes international cooperation.

The General Assembly gathers in yearly sessions to deliberate policy-making, discuss important issues of global concern such as peace and security, and handle budgetary matters for the U.N., playing a key role in the financing of peacekeeping.

The first session was held in 1946 shortly after the conclusion of World War II.

According to the U.N., every member state is legally obligated to pay their respective share towards peacekeeping based on a scale of assessments under a complex formula that they themselves have established.

The 71st session of UNGA kicked off last week in New York City and will see a few firsts and a few lasts.

President Obama will deliver his eighth and final remarks as president in what is expected to be a legacy-defining speech to tout key advancements he and his administration have made in their efforts to stabilize the world. This will also be the last time U.N. Secretary-General Ban Ki-moon of South Korea attends in his current capacity.

And it’s a new year of leadership as Fiji’s U.N. Ambassador Peter Thomson takes over as president-elect, the first time a representative of a developing Pacific island has been elected to the post.

What's on the General Assembly Agenda?

The General Assembly’s to-do list is filled with concerns of warfare, famine, disease and terrorism.

Some of those challenges include addressing North Korea’s nuclear tests, the civil war in Syria, and ratifying a climate change deal agreed to in Paris last year.

Obama is also scheduled to meet one-on-one with leaders of China, Colombia, Israel, Nigeria and Iraq.

Ahead of his meeting with Iraq’s prime minister, Obama acknowledged the weekend explosions, saying the U.S. partnership with Iraq must sustain its momentum in defeating ISIS, also called ISIL.

“We will continue to lead the global coalition in the fight to destroy ISIL, which is instigating a lot of people over the internet to carry out attacks,” Obama said Monday.

“We are going to continue to go after them. We're going to take out their leaders. We're going to take out their infrastructure. They are continuing to lose ground in Iraq and in Syria,” he said.

Refugee Crisis Takes Center Stage

An unprecedented 65.3 million people have been forcibly displaced from their homes, and there are nearly 21.3 million refugees in the world, according to the latest UNHCR estimates.

On Monday, world leaders adopted the New York Declaration for Refugees and Migrants to protect the rights of refugees and migrants, agreeing to share responsibility for large movements on a global scale.

Since 2000, there has been a 41 percent increase of international migrants and refugees, the overall number of migrants and refugees now topping 244 million.

On Tuesday, Obama is set to address the refugee crisis before the General Assembly. These meetings are an attempt to address one of the world’s most pressing problems.

The goal of these meetings is to secure global commitments to increase funding for humanitarian appeals and international organizations, admit more refugees through legal pathways including resettlement, and to provide refugees with education and work opportunities, according to the U.N.

U.N. Secretary-General Ban Ki-moon called Monday's declaration a breakthrough.

“More children can attend school; more workers can securely seek jobs abroad, instead of being at the mercy of criminal smugglers, and more people will have real choices about whether to move once we end conflict, sustain peace and increase opportunities at home,” he said.