GOP frontrunner Donald Trump insists he was joking when he tweeted that climate change was a “hoax invented by the Chinese.”

“I think that climate change is just a very, very expensive form of tax,” Trump said. “A lot of people are making a lot of money. I know much about climate change. I’ve received many environmental awards. And I often joke that this is done for the benefit of China — obviously I joke.”

Trump first tweeted in 2012 that “the concept of global warming was created by and for the Chinese in order to make US manufacturing non-competitive.”