The F-35, a fifth-generation stealth fighter, is the Pentagon's most expensive weapons system.

The Chinese J-31 fighter jet is believed to be a knockoff of Lockheed Martin's F-35.

Lockheed Martin Corp.'s F-35 jet in Fort Worth, Texas. Mike Fuentes | Bloomberg | Getty Images

President Donald Trump signed an executive memorandum Thursday that penalizes China for trade practices such as stealing American companies' intellectual property. The new measures impose retaliatory tariffs on about $60 billion in Chinese imports. On hand for the signing was Lockheed Martin CEO Marillyn Hewson, who oversees the Pentagon's most expensive weapons system, the fifth-generation F-35 Joint Strike Fighter. "We buy billions and billions of dollars worth of that beautiful F-35," Trump said before asking Hewson — whom he introduced as "Marillyn Lockheed" — to say a few words.

Hewson, who didn't react to Trump's mixup, said intellectual property is the "lifeblood" of the defense industry and welcomed the action taken by the Trump administration. "This is a very important moment for our country, in that we are addressing a critical area for the aerospace and defense industry and that is protecting our intellectual property," Hewson said. The F-35, the crown jewel in the defense giant's portfolio, had its sensitive design and electronics data compromised in 2009. Chinese hackers were believed to be behind the cyber intrusion. While the U.S.-made Lockheed jets are believed to have better computer software, sophisticated sensors and sensitive stealth coating, the theft of intellectual property gives adversaries the opportunity to avoid the expenses and delays involved with research and development.

Shenyang J-31 Gyrfalcon model exhibits on the Aviation Expo China. VCG | Getty Images

Meanwhile, China announced it was developing a fifth-generation fighter, as well. China's stealth Shenyang J-31 jet bears a remarkably striking resemblance to the F-35. Before the J-31 and the F-35, however, there was curious case of the J-20 and the F-22. In another instance of alleged industrial espionage, the prototypes of China's Chengdu J-20 stealth fighter jet looked suspiciously similar to the sleek design of Lockheed's F-22 Raptor.

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