The Trump administration's tariffs on steel and aluminum imports helped Nucor log its second-best earnings report ever, the steelmaker's Chairman, President and CEO John Ferriola told CNBC on Thursday.

Nucor reported its second-quarter results before Thursday's opening bell, topping Wall Street estimates on earnings per share and revenues.

Higher selling prices and shipments drove a record-breaking second quarter for the company, which makes steel products for numerous industries including the oil and gas space.

But Ferriola said that tariffs weren't the defining factor of Nucor's latest quarter.

"Let’s take a look at the facts," he said in an interview with "Mad Money" host Jim Cramer. "Certainly, we get a tailwind from the tariffs. But the tariffs really only have gone into effect, full effect, in June. So we’re just beginning to see the impact of that."

Ferriola noted that from the first half of 2017 to the first half of 2018, U.S. steel imports only dropped roughly 1 million tons, a "very small change" by industry standards, the CEO said.

"And that difference in the supply chain from imports [was] more than made up by domestic companies increasing their utilization," he added.

The CEO also highlighted Nucor's long-term strategy — which included pouring $8 billion into its business during the financial-crisis-driven downturn — as a driving factor in its recent success.

"Jim, you’ve heard me say on this show how many times that if Nucor had a level playing field on which we could compete, we would be very successful? And we are," he told Cramer. "And you’ve heard me also say that we’ve spent lots of money during the downturn preparing for the inevitable upturn in the steel market. Well, it’s here. We are capitalizing on it. There should be no surprise that we had a very strong quarter.”

Nucor is currently investing another $1.5 billion in "eight very strategic projects" slated for 2019 and 2020 launches that will create "good, high-paying American jobs for American workers," Ferriola said.

Nucor's stock slid 1.43 percent into Thursday's close, settling at $64.67 a share.