Former Secretary of State Rex Tillerson said he’s concerned with where trade talks with China stand, and he thinks it’s possible Beijing could wait until President Donald Trump is out of office before inking a new trade deal with the United States.

“Mutual respect, win-win solutions, these are things they want to hear and they’re not hearing those. It makes it hard for them to adjust themselves.”

Speaking at a conference in Houston on Wednesday, Tillerson, who was fired by Trump on Twitter, said the president hasn’t been dealing with China in a language that other countries want to listen to.

“Mutual respect, win-win solutions, these are things they want to hear and they’re not hearing those,” he said. “It makes it hard for them to adjust themselves.”

The big risk for Trump, Tillerson said, is that China has the luxury of simply waiting for his successor to take office, in 2021 or 2025, before coming back to the table to negotiate.

“If I had a concern about it, it’s that the Chinese I hope do not come to the conclusion that they can’t make a deal with this administration,” he said. “We’ll just wait for the next one. I hope that’s not what they’re moving to.”

Tillerson, the former Exxon Mobile CEO whom Trump called “dumb as a rock” on Twitter recently, also said he’s concerned that alliances built over the past 100-plus years have been weakened and eroded.

“I have some concerns about moving to strictly bilateral discussions that we are undermining or weakening that very strong alignment that’s been knitted together over the last century,” he said. “Russia, China, North Korea have no allies and friends. Our strength comes from allies and friends.”

Tillerson’s comments come as Trump told reporters Thursday that tariffs could be slapped on another $300 billion worth of Chinese imports, which would effectively be nearly everything the U.S. takes in aside from rare earths — which China is looking to weaponize should things continue to escalate.

“Our talks with China, a lot of interesting things are happening. We’ll see what happens … I could go up another at least $300 billion and I’ll do that at the right time,” Trump said, according to Reuters. “But I think China wants to make a deal and I think Mexico wants to make a deal badly.

Trade tensions with China escalated rapidly in early May after Trump tweeted Beijing was trying to renegotiate parts of a new trade deal that had already been settled. The Trump administration then raised tariffs on $200 billion worth of Chinese goods from 10% to 25%, and banned telecom giant Huawei from U.S. networks.

Beijing retaliated with tariffs on $60 billion worth of U.S. imports, hammering American farmers in the process, and is reportedly working on a list of “unreliable entities” to ban from its markets.

Editor’s note: Should Tillerson be speaking out against the president, his former boss, or are all bets off after Trump insulted his intelligence? Are Tillerson’s comments sour grapes, or are you worried about hurting alliances? Share your thoughts below.