With a few words in a largely conciliatory speech to the United Nations, Iran’s new president took aim at an Israeli fear: that international pressure on Tehran’s nuclear program could lead to scrutiny of Israel’s own secretive nuclear facilities. Israel is widely believed to ...

Hopeful yet unyielding, U.S. President Barack Obama and new Iranian President Hasan Rouhani both spoke up fervently for improved relations and a resumption of stalled nuclear talks Tuesday at the U.N. — but gave no ground on the long-held positions that have scuttled previous ...

A slowdown in warming that has provided fuel for climate skeptics is one of the thorniest issues in a report to be issued by U.N. experts on Friday. Over the past 15 years, the world’s average surface temperature rose far slower than many climate ...

North Korean scientists are able to build crucial equipment for uranium-based nuclear bombs on their own, cutting the need for imports that had been one of the few ways outsiders could monitor the country's secretive atomic work, according to evidence gathered by two American ...

Scientists will put pressure in the coming week on the U.N.’s troubled climate talks by releasing a report pointing to the dizzying challenge of meeting the international body’s global warming target. In the first volume of a massive trilogy, the Nobel Prize-winning Intergovernmental Panel ...

The world's chemical weapons watchdog begins examining the details of Syria's chemical arsenal while rebels agree to a cease-fire with jihadists in a key town.

In a sign Iran's government is loosening its grip on domestic security, several political prisoners, including a prominent human rights lawyer, are freed.

President Barack Obama seizes one last diplomatic chance to avoid military strikes on Syria but explains why the U.S. must retaliate for the alleged use of chemical weapons.