Raids at two apartments in Bangkok led police to issue warrants for two more suspects in the bombing at a Hindu shrine that killed 20 people two weeks ago.
Thailand's police chief did not offer details about who else might be involved in the deadly attack, though they asserted that Thai citizens were involved. At least 20 people died in Monday's bombing at a shrine.
Fighting between government forces and rebels has killed more than two dozen people in and near Damascus.
A truck bomb in central Kabul Friday killed eight and injured hundreds. Insurgents attacks have cause 70 percent of civilian casualties this year.
The airstrikes were prompted by intelligence indicating a likely Islamic State attack. The US said a deal has been reached with Turkey to use a key airbase.
But nine other tourists arrested in Inner Mongolia on a 47-day visit to ancient sites are being held on charges of 'criminal wrongdoing.' Those due to be released are from South Africa and Britain.