Sen. Marco Rubio on Monday criticized President Donald Trump‘s pledge to help Chinese technology company ZTE, saying he hopes the president is not “backing down” from his hawkish stance on China.

The Florida Republican’s criticism marks the first backlash to the president’s effort from a notable lawmaker within his own party. Trump’s reversal on ZTE, which he announced in a tweet Sunday, comes amid a high-stakes trade dispute between the world’s two largest economies.

In a tweet Monday morning, Rubio argued that the “problem with ZTE isn’t jobs & trade, it’s national security & espionage.” He said telecom companies “can be forced to act as a tool of Chinese espionage.”

“We are crazy to allow them to operate in U.S. without tighter restrictions,” the Senate Intelligence Committee member wrote.

Rubio tweet: Problem with ZTE isn’t jobs & trade, it’s national security & espionage. Any telecomm firm in # Chinacan be forced to act as tool of Chinese espionage without any court order or any other review process. We are crazy to allow them to operate in U.S. without tighter restrictions

Last month, the Trump administration barred U.S. companies from selling to ZTE, a telecommunications company, for seven years. The ban came in response to the firm shipping American goods to Iran and North Korea. It effectively crippled ZTE.

On Sunday, Trump said he and Chinese President Xi Jinping “are working together” to give ZTE “a way to get back into business, fast.” “Too many jobs” were lost in China, the president added. He said he instructed the Commerce Department to “get it done.”

Trump tweet: President Xi of China, and I, are working together to give massive Chinese phone company, ZTE, a way to get back into business, fast. Too many jobs in China lost. Commerce Department has been instructed to get it done!

Trump’s shift on ZTE appears to be a concession as Chinese Vice Premier Liu He gets set to travel to Washington this week for trade talks. The U.S. and China have threatened one another with tariffs that could damage the American agricultural industry. Trump has repeatedly pledged to punish Beijing for alleged trade abuses and theft of U.S. intellectual property by Chinese companies.

In a subsequent tweet Monday morning, Rubio wrote that “I hope this isn’t the beginning of backing down to China.”

Trump’s pledge to help ZTE already sparked criticism on the Democratic side of Congress. In a statement Monday, Senate Minority Leader Chuck Schumer said Trump is “backing off” his tough actions against China and argued his policy would “make China great again.”

House Intelligence Committee ranking member Rep. Adam Schiff, D-Calif., said Sunday that Trump “should care more about our national security than Chinese jobs.”

Schiff tweet