Obama: Killing Israelis 'is not resistance'

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Iran President Mahmoud Ahmadinejad

Beef with the U.S.: There are many, but sanctions against Tehran over nuclear technology is a top issue.

Background: In the past, Ahmadinejad has used the general debate as a forum to defend Iran's nuclear program and assail its arch foes Israel and the United States, typically prompting walkouts by the U.S. and some European countries.

Since the 1979 revolution that overthrew Iran's monarchy, Tehran and Washington have had no official relationship, a rift widened amid concerns about Iran's nuclear program and its human rights record.

A Holocaust denier, Ahmadinejad accuses "Zionists" of preventing U.S. President Barack Obama from improving relations with Iran.

Ahmadinejad has repeatedly said that Iran's nuclear program is for peaceful purposes and that it would not buckle to U.S. pressure to halt plans for further nuclear development.

He has scoffed at U.N. sanctions imposed on his country over its nuclear stance. The sanctions have limited Iran's ability to attract foreign investment, pinched its ability to import gasoline, created a drag on its shipping business and hurt Iranian banking relationships worldwide.

Michael Nagle  /  Getty Images

President Robert Mugabe of Zimbabwe

Beef with the U.S.: Sanctions imposed on the African nation.

Background: He has lashed out repeatedly against Western powers, telling them to go "to hell" over sanctions imposed on his ZANU-PF party.

The United States and European Union imposed sanctions on state firms and travel restrictions on Mugabe and dozens of his associates nearly 10 years ago, after a violent re-election campaign and often violent commercial farm seizures.

"We say to hell, to hell, hell with them," Mugabe said in August. "Sanctions must go, and they must go. They are hurting our people regardless of political affiliation."

The 86-year-old leader said he hoped Obama and new British Prime Minister David Cameron and his deputy Nick Clegg would move to mend ties between Harare and the West.

"They have imposed unjustified and illegal sanctions on us. The sanctions are comparable to the military aggression in Iraq," he said.

Meanwhile, Obama said he has been "heartbroken" by Zimbabwe's decline.

Mugabe was forced into a power-sharing pact with his rival, Prime Minister Morgan Tsvangirai, more than a year ago after a crisis over a 2008 national vote that observers say was marred by violence and fraud.

Spencer Platt  /  Getty Images

Nicaraguan President Daniel Ortega

Beef with the U.S.: He says the U.S. is a worldwide dictatorship.

Background: Since emerging as the leader in the Sandinista National Liberation Front during the Reagan years, Ortega has railed against what he views as U.S. hegemony. He has defended Iran's and North Korea's right to pursue nuclear technology.

In 1987, the Nicaraguan president addressed the world body as the Marxist leader of Nicaragua's Sandinista-run government.

He slammed U.S. policy in Central America and told then-President Ronald Reagan that "Rambo only exists in the movies." Reagan referred to Ortega as "the little dictator."

In 2007, Ortega said little had changed since his first visit to the U.N.

"The presidents of the U.S. change. And they may come to office with the greatest of intentions and they may feel that they are doing good for humanity, but they fail to understand that they are no more than instruments of one more empire in a long list of empires that have been imposed on our planet,” Ortega said, waving his arms.

The world is under "the most impressive, huge dictatorship that has existed — the empire of North America," he said.

He defended North Korean and Iran in their push for nuclear technology. Said Ortega: "And even if they want nuclear power for purposes that are not peaceful, with what right does (the U.S.) question it?"

Mario Tama  /  Getty Images

Libyan leader Moammar Gadhafi

Beef with the U.S.: Accuses U.S. of controlling the U.N. Security Council.

Background: Gadhafi made his first appearance at the U.N. last year. He slammed the Security Council and chastised the world body for failing to intervene or prevent some 65 wars since the U.N. was founded in 1945.

Gadhafi called for reform of the U.N. Security Council, which has 15 members, including the United States, and leads the world body's mandate to maintain international peace.

"It should not be called the Security Council, it should be called the 'terror council,'" he said. "Hence, the Security Council has been reduced to one country which controls it, therefore forming a danger to world peace."

Tensions were high following Scotland's release of Libyan Abdel Baset al-Megrahi, who was convicted of the 1988 bombing of Pan Am Flight 103, in which 270 people died.

Secretary of State Hillary Rodham Clinton and U.S. Ambassador to the U.N. Susan Rice left before Gadhafi even took the podium. Israel's U.N. delegation walked out during the speech.

Iran's president also left before the speech ended.

Ninety minutes into Gadhafi's 96-minute speech, an exhausted English-language interpreter passed out and was relieved by another translator.

Desmond Boylan  /  Reuters

Cuba's President Raul Castro

Beef with U.S.: Sees U.S. as enemy since 1959 Cuban revolution.

Background: When Cuba's parliament named Raul Castro president in 2008, it ended nearly 50 years of rule by his brother Fidel but left the island's communist system unshaken.

The United States and Cuba have not had formal diplomatic ties since 1961, though Washington is represented by a U.S. interest section in Havana.

Since 2009, Obama has eased travel and remittance restrictions imposed by his predecessor, George W. Bush, and resumed migration talks and direct postal service with the island.