KUWAIT CITY, KUWAIT - DECEMBER 13: Czech soldiers in chemical protection suits take part in a chemical attack response drill conducted at the U.S. Embassy by civil defense authorities and troops from the United States, Germany, and Czech Republic December 13, 2002 in Kuwait City, Kuwait. The exercise, dubbed 'Event Horizon,' was staged to test the coordinated emergency response to a mock attack on the U.S. Embassy in Kuwait by terrorists using deadly sarin nerve gas.
What are nerve agents like Novichok and how do they kill?
Novichok, a highly poisonous chemical, was designed by Russia during the Cold War and made to be undetectable by standard detection equipment. CNN explores how it, and other nerve agents, work.
01:34 - Source: CNN
Crisis in Syria 16 videos
KUWAIT CITY, KUWAIT - DECEMBER 13: Czech soldiers in chemical protection suits take part in a chemical attack response drill conducted at the U.S. Embassy by civil defense authorities and troops from the United States, Germany, and Czech Republic December 13, 2002 in Kuwait City, Kuwait. The exercise, dubbed 'Event Horizon,' was staged to test the coordinated emergency response to a mock attack on the U.S. Embassy in Kuwait by terrorists using deadly sarin nerve gas.
What are nerve agents like Novichok and how do they kill?
01:34
Now playing
- Source: CNN
Damon Syria DMZ pkg 2
Exclusive: Inside Syria's demilitarized zone
02:27
Now playing
- Source: CNN
Vaciha Turki Al Omar, 30, has been in Idlib for seven months. She on the hill overlooking the sprawling refugee camp with her kids. "We can try to fight but the kids are our weakness so we must run away," she says.
Major rebel stronghold in Syria under threat
03:54
Now playing
- Source: CNN
Lead Martin Savidge on Florence live Jake Tapper_00022318.jpg
Cat 3 Florence coming in like a 'Mike Tyson punch'
04:15
Now playing
- Source: CNN
idlib syria frontlines pleitgen 2
CNN travels to the front lines of Idlib
01:49
Now playing
- Source: CNN
rebuild syria
Syrians rebuild war-torn historic city of Homs
02:15
Now playing
- Source: CNN
white helmets
White Helmets evacuated into Jordan by Israel
02:10
Now playing
- Source: CNN
syria girl prosthetic legs tin cans nr vpx_00000425
Girl's new prosthetic legs replace tin cans
00:56
Now playing
- Source: CNN
syria golan heights fleeing lee pkg_00002705.jpg
Thousands flee toward closed borders
02:15
Now playing
- Source: CNN
A day in the life of an artist-turned-barber Syrian refugee living in the Zaatari Refugee Camp in Jordan.
A day in the life of a Syrian refugee
04:03
Now playing
- Source: CNN
Arwa Damon Syria Refugee Camp 04 14 2018
CNN goes inside refugee camp after airstrikes
02:20
Now playing
- Source: CNN
airstrike syria
Video reportedly shows airstrike in Syria
01:29
Now playing
- Source: CNN
US President Donald Trump addresses the nation on the situation in Syria April 13, 2018 at the White House in Washington, DC. Trump said strikes on Syria are under way.  / AFP PHOTO / Mandel NGAN        (Photo credit should read MANDEL NGAN/AFP/Getty Images)
Trump's message to Iran and Russia
01:02
Now playing
- Source: CNN
Trump Assad Putin SPLIT RESTRICTED
Could the Syrian war lead to a US-Russia conflict?
01:42
Now playing
- Source: CNN
This image released early Sunday, April 8, 2018 by the Syrian Civil Defense White Helmets, shows a child receiving oxygen through respirators following an alleged poison gas attack in the rebel-held town of Douma, near Damascus, Syria. Syrian rescuers and medics said the attack on Douma killed at least 40 people. The Syrian government denied the allegations, which could not be independently verified. The alleged attack in Douma occurred Saturday night amid a resumed offensive by Syrian government forces after the collapse of a truce. (Syrian Civil Defense White Helmets via AP)
Syrian attacks escalate tensions among global powers
01:59
Now playing
- Source: CNN
Syria Ghouta destruction
Families bused out of chemical attack city
00:47
Now playing
- Source: CNN