Chemical weapons

Hong Kong's top health official has claimed that tear gas used by police on protesters poses no public health risk, days after police were reported to use the gas at a university campus. Some have expressed fears that the chemical weapon used in the city could contain the toxic pollutant dioxin.

Newsweek spoke to several chemical weapons experts on why the devastating substance continues to be used without international accountability.

"This very much looks like it was caused by white phosphorus," British chemical weapons expert Hamish de Bretton-Gordon told "The Times of London."

While the president criticized Russia and Iran during the Security Council meeting, he expressed appreciation for the "restraint" both nations have shown in Syria's Idlib province.

Bob Woodward's "Fear: Trump in the White House" will be released on September 11.

There have been hundreds of chemical attacks in Syria since 2011, but Bashar al-Assad continues to be protected by his Russian allies.

Novichok kills by disrupting communication between nerves and muscles or nerves in the brain.

Most international observers believe Syrian President Bashar al-Assad was behind the attack, with the support of his Russian allies.

Police believe the suspect was following an ISIS guide for making a ricin bomb.

Chemical weapons such as chlorine and the banned nerve agent sarin gas were likely used in the attack.

Forces loyal to Syrian President Bashar al-Assad have been accused of launching the strike on the rebel-held town.

Foreign Minister Sergei Lavrov said Moscow warned the Americans of its "red lines."

Every day those 2,000 U.S. troops remain in Syria, we remain saddled with enormous strategic risk.

U.S. ambassador to the United Nations Nikki Haley cautioned that chemical attacks similar to those in Syria "could happen" in the United States doesn't take more precautions domestically.

Alexander Zasypkin said any U.S. missiles fired at Syria would be downed by Russian defenses.

Assad was supposed to have given up his chemical weapons under a deal reached in 2013.

Stephen Colbert quizzed the leading diplomat about whether Trump's critique of Obama's Syria policy is the right one.

In an angry address to the United Nations, Russia's envoy implied rebels staged the alleged chemical attack.

In his crudely cynical manner, Bashar al-Assad may be banking on US President Donald J. Trump's recent public statements about wanting to be out of Syria quickly. 

How will the president follow up his critical tweet?

The Russian Embassy in London said British accusations of Kremlin involvement "are nothing but assumptions."

Sergei Skripal and his daughter are being kept heavily sedated and are still unable to communicate two weeks after they were poisoned.

An ex-spy, his daughter and a police officer are seriously ill. So what exactly is Novichok?

North Korean defectors have said chemical weapons are used against prisoners and disabled people.

North Korea and Syria have a history of working together against what they view as U.S. imperialism. In recent years, they've both seen success.

An account affiliated with Turkey's so-called Operation Olive Branch claimed Kurdish fighters attacked the Free Syrian Army with chlorine gas.

Israel feared a large-scale chemical weapons attack.

North Korea is estimated to possess between 2,500 to 5,000 metric tons of weaponizable chemical agents.

The U.S. does have a history of controversial medical experiments elsewhere.

Traditional foes of U.S. foreign policy, such as Cuba, Iran, North Korea and Russia, are increasingly eager to cooperate against Trump.