U.N. chief Antonio Guterres spoke on Tuesday.

He spoke to world leaders.

It was his last big speech.

He said the world must work together.

He said wars and hot weather divide people.

He said artificial intelligence divides people too.

He said leaders must not lose trust.

He leaves his job at the end of this year.

So his words feel urgent.

He told big powers they are not so strong.

He said armies alone cannot make peace.

About an hour later, U.S. President Donald Trump spoke.

He had a different idea.

He said he used strength.

He made America the most powerful country.

Trump said the U.N. has great potential.

But he criticized the U.N.

He said it pushes a far-left global plan.

He also criticized the International Criminal Court.

The U.S. is not part of it.

The meeting will talk about wars.

There are wars in Iran, Gaza, Ukraine, Sudan, Congo and Myanmar.

Leaders want to end them.

They will also talk about global warming.

They will talk about inequality.

They will talk about money problems.

These come from blocked shipping routes and supply chains.

They will talk about the U.N. itself.

They want to change the Security Council.

Guterres ends his second five-year term on Dec. 31.

No clear new leader has appeared.

He said he will never give up on U.N. values.

Then he left the stage.

People stood and clapped for a long time.

About 130 leaders will speak.

Trump and French President Emmanuel Macron spoke Tuesday.

Ukraine's Volodymyr Zelenskyy and Iran's Masoud Pezeshkian speak Wednesday.

Israeli Prime Minister Benjamin Netanyahu speaks Thursday.

Palestinian President Mahmoud Abbas cannot come.

The U.S. said no to his visa.

But he will speak by video the same day.

China's Xi Jinping, Russia's Vladimir Putin and India's Narendra Modi will not come.

France's U.N. ambassador Jerome Bonnafont spoke.

He said it is very important for leaders to support the U.N.

He said the U.N. is a place for talking, not fighting.