U.S. prepared to do more in Syria, hopes not necessary - U.N. envoy

UNITED NATIONS (Reuters) - The United States took a very measured step that was "fully justified" when it fired missiles at a Syrian air field over a deadly toxic gas attack, said U.N. Ambassador Nikki Haley on Friday.

"We are prepared to do more, but we hope that will not be necessary," she told the U.N. Security Council. "The United States will not stand by when chemical weapons are used. It is in our vital national security interest to prevent the spread and use of chemical weapons."