President-elect Donald Trump gave Venezuelan President Nicolas Maduro a stern warning on Thursday not to harm his country’s opposition leader.

Venezuelan President Nicolas Maduro, whose nearly 12 years in office have been marked by a deep economic and social crisis, was sworn in for a third term on Friday, staying in power despite a six-month dispute over an election and international calls for him to stand aside.

President-elect Donald Trump urged Venezuela not to harm opposition leader María Corina Machado after she was briefly arrested on Thursday, in his first public comments on the country’s disputed election.