(Carolyn Kaster/AP)

“People say, ‘Well, he killed 100,000 people. What’s the difference with this 1,400?’ With this 1,400, he crossed a line with using chemical weapons. President Obama did not draw the red line. Humanity drew it decades ago, 170-some countries supporting the convention on not using chemicals — chemical warfare.”

— House Minority Leader Nancy Pelosi (D-Calif.), Sept. 3, 2013

One of the administration’s main arguments for attacking Syria is because the government crossed an important line by using chemical weapons against its own people.

Rep. Nancy Pelosi, a strong supporter of military strikes, echoed that argument on Tuesday. She noted that as far back as 1925, nearly 40 nations had joined together to ban the first use of chemical weapons when the Geneva Protocol was signed. (Her mention of 170 countries appears to refer to the 1993 Chemical Weapons Convention, which seeks to prohibit the production of chemical weapons and mandates their destruction; Syria has refused to sign the treaty, though 189 other countries have signed it.)