MANILA, Philippines (AP) — International drug enforcement officials say methamphetamine is the drug of choice in Asia but new synthetic drugs have found their way in the region, with authorities constantly playing catch up with traffickers.

Joseph Reagan, U.S. Drug Enforcement Administration regional director for the Far East, said Tuesday the legal system in many countries could not react fast enough to synthetic marijuana and synthetic cathinones, sometimes called bath salts. Once legislatures address the specific substance, traffickers change one chemical molecule to make a drug that is temporarily legal.

Reagan spoke Tuesday while attending a regional drug enforcement conference in Manila. He says the United States has a significant problem with synthetic drugs, which have also been found in Indonesia, Malaysia, Japan, South Korea and the Philippines.