Obama confronts Iran, Syria

• Violence in the Middle East and a civil war raging in Syria are expected to be center stage
• U.S. President Barack Obama is scheduled to speak Tuesday
• Afghan President Hamid Karzai is also expected to address delegates
• On Monday the U.N. General Assembly convened a high-level meeting on the rule of law

United Nations (CNN) -- World leaders will again take up a host of pressing humanitarian issues, including poverty, global warming and the prospect of renewed conflicts in sub Saharan Africa, when the United Nations General Assembly Debate officially opens in New York Tuesday morning.

But violence in the Middle East and an 18-month civil war raging in Syria are expected to remain center stage, particularly after international peace envoy Lakhdar Brahimi on Monday appealed for definitive change in the region.

"Reform is not enough anymore," he said of the continued violence gripping Syria. "What is needed is change."

Tuesday's highly anticipated speakers include Secretary General Ban Ki-moon, who has been critical of Syrian President Bashar al-Assad though largely unable to stem the bloodshed, and U.S. President Barack Obama, who remains entrenched in a hard fought re-election campaign.

Obama's speech will be his fourth at the General Assembly podium, and comes on the heels of a series of confrontational statements by the Iranian president, who declared Monday that Israel had no roots in the Middle East.

U.S. national security spokesman Thomas Vietor called the comments "disgusting, offensive and outrageous," and that they "underscore again why America's commitment to the security of Israel must be unshakeable, and why the world must hold Iran accountable for its utter failure to meet its obligations."

While Obama is speaking in front of an international crowd, his speech Tuesday will also largely target a domestic audience, which will decide in November whether he gets another chance at the presidency.

French President Francois Hollande is scheduled to take the lectern later that afternoon and is expected to address a worsening crisis in the Sahel, where a deadly mix of drought, famine and Islamic militancy have plagued the North Africa region.

Afghan President Hamid Karzai is also expected to address delegates. He arrived last year but didn't give his speech, returning early after former president and peace envoy Burhanuddin Rabbani was assassinated.

On Monday, the U.N. General Assembly convened a high-level meeting on the rule of law which sought to highlight the importance of existing international treaties as well as the International Criminal Court.

"The wider body of international law developed at the United Nations gives the international community a basis to cooperate and peacefully resolve conflicts and the means to ensure that there is no relapse of fighting," said Secretary Ban.

During a separate U.N. meeting on Haiti, which included actor-activist Sean Penn, Haitian Prime Minister Laurent Lamothe called on aid groups to do more to assist the earthquake-ravaged Caribbean nation.

"Haiti has no social protection system," the prime minister said, noting that part of the problem stemmed from a lack of government services outside the capital of Port-au-Prince.

More than two years after the 2010 quake forced an estimated 1.5 million residents into makeshift housing, Lamothe said about 400,000 of them are still waiting to be relocated.