Berkshire Hathaway purchased $123 million worth of shares in Occidental Petroleum. Even more interesting, over the past 18 months, Buffett has bought $13 billion worth of Occidental shares, bringing his total investment in the oil-producing giant to more than 25 percent.

Buffett has also been busy gobbling up shares of oil-producer Chevron. Berkshire Hathaway currently holds close to $26 billion in Chevron stock.

At his recent annual meeting, Buffett made it clear that he thinks oil production remains central to U.S. prosperity. “In the United States, we’re lucky to have the ability to produce the kind of oil we’ve got from shale,” he said. He also declared, “We do not think it’s un-American to be producing oil,” and vowed, “We will make rational decisions” in reference to fossil fuel investment.

Moreover, Buffett seems to be suspicious of environmental, social, and governance (ESG) investing, which seeks to divest in fossil fuel companies while promoting nebulous social justice causes, even when these efforts reduce returns for investors.

In fact, Buffett has referred to ESG as “asinine,” and believes it belies Berkshire Hathaway’s sole purpose: increasing returns for clients.