As many as 22 people in South Korea and four U.S. lab workers may have been exposed to anthrax after the American military accidentally shipped out at least one live sample, officials said.

The four lab employees were undergoing medical treatment as a precaution after the military sent the sample inside the country to a commercial lab in Maryland, U.S. officials said Wednesday.

U.S. Secretary of State John Kerry is set to launch a final high-stakes diplomatic push to seal a ground-breaking nuclear deal with Iran, as some officials warned Wednesday the negotiations may go beyond a June 30 deadline.

Kerry will on Saturday once again huddle with his Iranian counterpart Mohammad Javad Zarif in Geneva, after weeks of behind-the-scenes complex technical discussions in Vienna seeking to narrow the gaps on what would be an unprecedented deal on curtailing Iran's nuclear program.

A U.S. appeals court on Tuesday dealt another blow to President Barack Obama's efforts to grant amnesty to millions of illegal immigrants.

The U.S. Court of Appeals for the Fifth Circuit in New Orleans rejected a request from the Obama administration that it lift an injunction barring it from carrying out a measure that would have protected some four million undocumented foreigners from deportation.

U.S. Senator Bernie Sanders formally launched his populist, liberal campaign for the White House on Tuesday, reiterating his pledges to recalibrate an American economic system which created sharp disparities between rich and poor.

Sanders, who had said last month he planned to stand in the election, told a launch event in Vermont he was running to support the interests of American voters tired of a "rigged" system.

The governor of Nebraska, citing public safety concerns, on Tuesday vetoed legislation that would have ended the death penalty in the western American state.

Pete Ricketts, a Republican, said repealing capital punishment "sends the wrong message" to the "overwhelming" number of Nebraskans who want to see it remain the law of the state.

Nearly 7,000 people in Canada's Alberta province have been evacuated from the path of wildfires which threaten to ravage homes and businesses, including oil refineries in the region, officials said Tuesday.

More than 1,600 firefighters are battling the 70 wildfires, 55 of which were sparked by lightning on Sunday.

A 40-year-old Yemeni, who fought U.S. troops in Iraq and Afghanistan, pleaded guilty in New York Tuesday to conspiring to murder Americans and to supporting al-Qaida, prosecutors said.

Saddiq al-Abbadi, who was arrested with an alleged co-conspirator in Saudi Arabia on a U.S. warrant, now faces a maximum life sentence in an American jail.

A Bangladeshi peacekeeper was shot dead and another wounded, the United Nations said Tuesday, in the second attack in days in Mali's capital on what is considered the world's most dangerous U.N. mission.

A statement from MINUSMA, the U.N.'s peacekeeping force in Mali, said "an incident" involving one of its vehicles took place in the area of Bamako airport.

Japanese troops will take part in a major U.S.-Australian military exercise for the first time in July, as Washington looks to bolster links among its allies in the face of an increasingly assertive China.

Japan's Ground Self-Defense Force (JGSDF) -- its army -- will send 40 personnel to participate in Talisman Sabre, a two-yearly drill that begins on July 7, which will involve around 27,000 servicemen, a spokesman told Agence France Presse.

A Sydney mother has abandoned her two children and fled to Syria for a new life under the Islamic State group, media reported Tuesday, becoming one of more than 100 Australians who have joined the jihadists.

The Australian government said it was deeply disturbed by the report and that it was monitoring the situation closely.