By: Larisa Epatko

Iranian President Mahmoud Ahmadinejad signs a guest book as U.N. Secretary-General Ban Ki-moon looks on before their meeting on Sunday. Photo by Allison Joyce/Getty Images.

When more than 120 world leaders and envoys meet at the United Nations this week, they are expected to discuss the deteriorating situation in Syria and tensions over a nuclear Iran, but not much "substantive diplomacy" is expected. We've rounded up some things to look for this year:

Blink and You Might Miss Him

What's notable is how little time President Obama will spend at the U.N. General Assembly, said Colum Lynch, who covers the United Nations for the Washington Post. The president will speak Tuesday and will meet with U.N. Secretary-General Ban Ki-moon. But he had no other formal bilateral meetings with other countries planned at press time.

"Even when you go back to George Bush, it's extremely rare for a U.S. president not to at least spend the first day (in meetings) or go to the secretary-general's luncheon," said Lynch. "I think that's noteworthy in the sense that it shows the Americans don't want to be drawn into messy debates about Syria," or emphasize their differences with Israel over Iran.

"So I suspect that there will be very tough language about all these issues — about Syria and Iran and elsewhere — but there will not be much substantive diplomacy," Lynch said.

What Will Iran Say?

The possible confrontation between Iran and Israel over Tehran's nuclear program — and whether it is developing a nuclear weapon — makes Iran one to watch at the U.N. General Assembly, said Lynch.

The United States is at odds with Israel about how to handle Iran, and President Obama is not planning to meet with Israeli Prime Minister Benjamin Netanyahu, who has said the United States must create a "red line" that Iran cannot cross.

Ronen Bergman, reporter for Yedioth Ahronoth newspaper, discussed U.S. concerns that Israel might launch a pre-emptive strike on Iran in this Sept. 11 NewsHour interview:

Although Iranian President Mahmoud Ahmadinejad "is not the most influential person in Iran … (he'll) get a fair bit of attention" when he speaks on Wednesday because of the possible confrontation with Israel and the political rhetoric, Lynch said.

In anticipation of Ahmadinejad's usual fiery rhetoric, Ban asked the Iranian leader to tone it down this year, according to a U.N. press release. Ban "drew attention to the potentially harmful consequences of inflammatory rhetoric, counter-rhetoric and threats from various countries in the Middle East," the press release said. The question is, will he?

Fireworks over Syria

Besides the usual themes of development, poverty, climate change, security and peace-keeping in world leaders' speeches at the U.N. General Assembly, a big focus this year is expected on the continued turmoil in Syria.

"Syria will be the most important issue because not only is the West interested in banging the drum on it, but also the Arab World will be very outspoken on it," Lynch said.

"There's a lot of frustration that the U.N. hasn't been able to close a deal, there's frustration with the parties for pursuing a military outcome, and there will be sniping between the Americans and the Russians and Chinese over the approach."

Palestinian Status

Last year, Palestinian leader Mahmoud Abbas submitted an application for formal U.N. membership, which would have entailed recognizing the state of Palestine. The effort stalled in the U.N. Security Council.

So this year, the Palestinians are expected to take a different approach. They reportedly will seek to elevate their status a notch from permanent observer to non-member observer status. Abbas will announce the move during his speech on Thursday, reports CNN.

Revisiting the Arab Spring

With new governments setting up after the Arab Spring in Yemen, Egypt and Libya, their leaders will get attention when they speak this year on Wednesday (Yemen and Egypt) and Thursday (Libya).

Also likely to bring up the Arab Spring are Qatar (on Tuesday) and Turkey (scheduled for Friday), whose governments were diplomatic players during the regional revolutions, said Lynch.

You can watch the speeches live here on the Rundown, when they start on Tuesday. We'll also live-blog events at the U.N. General Assembly from Tuesday through Thursday. View all of our World coverage.