UNITED NATIONS (AP) — U.S. Ambassador Nikki Haley says the U.N.'s failure to hold Syria accountable for its use of chemical weapons has made the world "a far more dangerous place."

She told the Security Council Wednesday that its lack of action on Syria has led others to take notice, pointing to the use of nerve agents against North Korean leader Kim Jong Un's half-brother in Malaysia and the poisoning of a former spy and his daughter in England.

Haley called this "a dangerous trend."

The U.S., Britain, France and Germany issued a joint statement marking Tuesday's first anniversary of a deadly sarin gas attack on the rebel-held Syrian town of Khan Sheikhoun blamed on the Syrian government. They condemned chemical weapons use anywhere and vowed to ensure those responsible are held accountable.