Tiger Woods' plane is back in Switzerland where he recently attended a rehab program ... TMZ has confirmed.

The golfer's private jet left Florida Saturday night and landed in the European country Sunday.

We don't know why Woods' plane landed in the country ... and we've reached out to his team for more information -- but it's an interesting place to go given he just recently checked himself into rehab there.

Remember ... after Woods was arrested and charged with DUI last month, he entered a rehab program in Switzerland -- going overseas to protect his privacy.

However, we learned he was flying back to the United States earlier this month ... touching down in Palm Beach, Florida.

We didn't know at the time if that meant his rehab was completely over ... and, given he's now headed back, there seems to be a chance he's still working on his recovery.

Woods is facing two misdemeanor charges (and one traffic citation), driving under the influence and refusal to submit to a lawful test for his late March crash. He has pled not guilty to the charges against him.