I wouldn’t know. There are toilets in the US that use a high pressure flush, but they still have a siphon. It’s there so that the toilet can flush without water pressure from the mains (you can flush a toilet by dumping a bucket of water in it) and it also forms a seal that prevents sewer gas from flowing back up through the toilet. So even if the toilet uses an alternate flushing method, it probably still has a siphon.