Obama to the World: We Need to Unite

In his first speech to the United Nations General Assembly, President Barack Obama bluntly pushed for the international community to work together in meeting new challenges and fulfill its responsibility swiftly.

"The time has come for the world to move in a new direction," Obama said in a speech that lasted more than 30 minutes and invoked his campaign rhetoric of hope and change. "We must embrace a new era of engagement based on mutual interests and mutual respect, and our work must begin now."

Video of President Obama addressing the United Nations general assembly on international responsibility.Play

Outlining the work the United States has done for its part, Obama admonished those who use anti-Americanism "as an excuse for our collective inaction."

"Make no mistake: this cannot be solely America's endeavor. Those who used to chastise America for acting alone in the world cannot now stand by and wait for America to solve the world's problems alone. We have sought, in word and deed, a new era of engagement with the world. Now is the time for all of us to take our share of responsibility for a global response to global challenges," Obama told attendees.

The president outlined what he called "four pillars" for the future: "non-proliferation and disarmament; the promotion of peace and security; the preservation of our planet; and a global economy that advances opportunity for all people."

Video of President Obama telling the UN general assembly that he ordered the closure of Guantanamo.Play

Afghanistan Tops U.S. List of International Challenges

As Obama tried to push attendees toward mutual cooperation, the administration is rethinking its strategy for Afghanistan and what to do next in the war that is growing increasingly unpopular.

Obama today reaffirmed, in strong rhetoric, his administration's commitment to fighting al Qaeda in Afghanistan.

"We will permit no safe-haven for al Qaeda to launch attacks from Afghanistan or any other nation," Obama said. "We will stand by our friends on the front lines, as we and many nations will do in pledging support for the Pakistani people tomorrow. And we will pursue positive engagement that builds bridges among faiths, and new partnerships for opportunity. But our efforts to promote peace cannot be limited to defeating violent extremists."

VIDEO: The U.S. Ambassador to the U. N. speaks about Afghanistan and missile defense.Play

The war in Afghanistan is one of Obama's greatest international challenges, both domestically and abroad. Internally, the White House is hesitant to commit more troops to the region unless there are sure signs the strategy there is working. The top general in Afghanistan, Gen. Stanley McChrystal, is likely to request more troops to combat the growing influence of al Qaeda and the resurgence of the Taliban in the war-torn country.

The president is exploring alternatives to a major troop increase, including a plan from Vice President Joe Biden to focus more on rooting out al Qaeda and the Taliban on the Pakistan-Afghanistan border, a strategy that could entail reducing troops.

"We're going to look very seriously at the circumstances on the ground, both political, security and economic, and how to best accomplish the goal of disrupting, dismantling and defeating al Qaeda," U.S. ambassador to the U.N., Susan Rice said on "Good Morning America" today. "The circumstances in Afghanistan are complex and evolving in the wake of the elections. It would be foolhardy for the United States and its partners not to take account of the circumstances as they evolve and adjust our goals accordingly."

In a reception hosted by the first couple this evening, Obama will thank the countries contributing the most troops and police forces to the U.N. efforts in Afghanistan, which include Bangladesh, Ethiopia, Ghana, Italy, Pakistan, Rwanda and Uruguay.

In an interview Tuesday at Fortune's most powerful women summit, former Secretary of State Condoleezza Rice underlined her view of the consequences of failure.

"The last time we left Afghanistan, and we abandoned Pakistan ... that territory became the very territory on which al Qaeda trained and attacked us on September 11. ... It's that simple," she told Fortune. "If you want another terrorist attack in the U.S., abandon Afghanistan."

Tough Words for Iran, North Korea

As he pledged to move forward with the ratification of the Test Ban Treaty, designed to prevent the spread of nuclear weapons and related technology, Obama had some tough words for Iran and North Korea on their pursuit of nuclear technology.

"Those nations that refuse to live up to their obligations must face consequences. This is not about singling out individual nations -- it is about standing up for the rights of all nations that do live up to their responsibilities," Obama said.

"Because a world in which IAEA [International Atomic Energy Agency] inspections are avoided and the United Nation's demands are ignored will leave all people less safe, and all nations less secure. In their actions to date, the governments of North Korea and Iran threaten to take us down this dangerous slope," the president said.

Obama's first address at this forum was closely watched by both his rivals and allies in the audience, a group that included Iran's defiant leader Mahmoud Ahmadinejad and countries that have long supported him, including Russia and China.

"The message to Iran is it has a choice," Susan Rice told "GMA." "It can uphold its international responsibility, abandon nuclear weapons or face more pressure from United States and others."

Obama will meet Russian President Dmitry Medvedev this afternoon, hoping for better luck pressing the proverbial reset button. The United States' decision last week to replace permanent bases with larger missiles in Poland and the Czech Republic with smaller and more mobile missiles in Europe was welcomed by Russia, which has long said the United States' missile-defense program threatens its national security. The White House hopes that step will make Russia more inclined to help convince Iran to end its nuclear weapons program.

Ahmadinejad, for his part, said the nuclear issue is not even on its agenda.

"The discussion on the nuclear issue is certainly free and open," Ahmadinejad said in an interview with The Associated Press. "We will not seek to avoid any form of discussion or prevent it. But it's really not on our agenda. We believe that nuclear weapons are the source of threats and instability. So global will is required to achieve full nuclear disarmament. Secondly, we need to pave the way to increase opportunities for the peaceful use of nuclear technology and energy."

Foreign Policy Challenges Facing Obama

In the past 24 hours alone, Obama has faced a rash of foreign policy challenges, from failure to find consensus on climate change with China to escalating trade tensions with the country to resistance on Middle East peace process talks.

The president met Tuesday with Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas and conveyed his frustration to the leaders.

In his speech today, Obama again made a call for a two-state solution.

"We continue to call on Palestinians to end incitement against Israel, and we continue to emphasize that America does not accept the legitimacy of continued Israeli settlements," Obama told the U.N. General Assembly. "The time has come to relaunch negotiations -- without preconditions."

At Tuesday's meeting, officials said the president gave a "hard push" and expressed impatience to both leaders for failure to take enough steps to resume peace talks.

"We can't continue to talk about talking," Rice told "GMA." Now is the time for serious discussion."