Leaders attending the Group of 20 summit in Pittsburgh will seek to forge agreements to buoy a global economic recovery and repair financial imbalances that contributed to the recession.

The United States has pursued missile defense technologies for six decades, with mixed results. Changes under the Obama administration, including adjustments to planned defenses in Europe, could portend a new direction.

U.S. missile defense in the twenty-first century is focused on emerging threats from North Korea and Iran, but critics say these systems are too costly and largely unproven.

The African Union succeeded the old Organization for African Unity (OAU) in 2002. Since then, the new institution has struggled to reform governing bodies inherited from the OAU while shouldering challenging new peacekeeping missions.

An overview of Peruvian terrorist groups, Shining Path and Tupac Amaru.

Opposition victory in Japan's 2009 parliamentary election served as a watershed moment in the country's electoral politics. Analysts say political change in Tokyo could result in a possible shift in its close relationship with the United States, especially in security matters.

The Revolutionary Armed Forces of Colombia (FARC) and the National Liberation Army (ELN) are Colombia's two predominant rebel groups. While both have been depleted in recent years, they remain destabilizing forces.

India's growing economic and political influence in Afghanistan has angered Pakistan, the traditional power there, and has experts worried that Afghanistan could become another battleground in the long-standing rivalry between South Asia's two giants.

Taiwan, whose leaders continue to talk about independence, remains a focal point of Chinese military modernization.

Countries in sub-Saharan Africa lose billions of dollars each year through corruption, say analysts. Local and international efforts to reform governance have been inconsistent.

The crisis following Iran's presidential vote cast a new light on the country's hotly contested media space. A crackdown has limited independent reporting but other sources remain as channels for dissent.

Brazil's economic dynamism has given it a stronger voice on global trade and energy issues. Experts say Washington can advance its regional interests more effectively through a more sophisticated relationship with Brazil.

China remains Pyongyang's biggest trade partner and arguably has most leverage on Kim Jong-Il's regime. But the relationship is a difficult one, experts say.

As the United States looks to reform its health care system and expand access to the uninsured, countries that have moved toward universal health care may offer lessons.

A profile of militant extremist groups in the disputed Himalayan region of Kashmir.

As China continues to transform its economy, rising tensions and spates of violence within its primarily Muslim Uighur community is causing regional instability both internally and with Pakistan.

Experts say graduating Russia from Cold War-era legislation linked to emigration and trade would be a step toward warming relations with Moscow.

A profile of the Southeast Asian terror group Jemaah Islamiyah, the group allegedly responsible for the 2002 Bali bombings.

Washington is focusing new military aid to Pakistan on strengthening counterinsurgency capabilities. But distrust between the two countries and Islamabad's continued focus on an Indian threat pose challenges, say experts.

Iran's Supreme Leader remains the regime's ultimate authority but controversy surrounding the country's June 12 presidential election has raised new questions about the role and power of the head of state.