Gas Mask

A US soldier wears a gas mask during a competition to test individual skills at a US Army base in Uijeongbu, north of Seoul, on July 8, 2015. The goal of the competition is to foster esprit de corps across the units participating and to continue to strengthen the US-South Korea alliance.

Jung Yeon-Jejung/AFP

A US soldier wears a gas mask during a competition to test individual skills at a US Army base in Uijeongbu, north of Seoul, on Wednesday. The goal of the competition is to foster esprit de corps across the units participating and to continue to strengthen the US-South Korea alliance

An Israeli woman carries her son and gas masks for her family outside a gas masks distribution center in Tel Aviv, Israel, Wednesday, Aug. 28, 2013. Large crowds of Israelis have lined up at gas-mask distribution centers across the country in anticipation of a possible Syrian attack on Israel. (AP Photo/Oded Balilty)

Oded Balilty/AP

An Israeli woman carries her son and gas masks for her family outside a gas masks distribution center in Tel Aviv, Israel on Wednesday. Large crowds of Israelis have lined up at gas mask distribution centres across the country in anticipation of a possible Syrian attack on Israel.