In the typewritten letter, posted in Bangkok, the Yellow Red Overseas Organisation claimed to be an anti-American group that would attack embassies, airlines and public transport in eight countries before the end of the month. It warned of attacks against Australia, South Korea, Japan, Thailand, The Philippines, Singapore, Kuwait and Pakistan. Thai police stepped up security at the embassies and said they were taking the letter seriously. But senior security officials, who didn’t want to be named, said they had never heard of the organisation. “The most likely explanation may be that someone who is upset South Korea is getting ready to send 3000 troops to Iraq wants to put pressure on the South Korean government,” he said.