In a series of tweets before a scheduled announcement from the White House on Thursday about new tariffs on steel and aluminum, Tesla CEO Elon Musk suggested to President Trump that the U.S. should seek more “equal & fair” trade rules for cars with China.

The tweets came one day after Trump wrote that his administration had asked Beijing to cut the annual U.S. trade deficit by $100 billion (though his tweet mistakenly listed the amount at $1 billion). Musk responded:

— Elon Musk (@elonmusk) March 8, 2018

— Elon Musk (@elonmusk) March 8, 2018

Musk toldThe Verge that it’s “better if all countries lower tariffs.” However, Trump said he plans to institute what he calls “mirror” taxes on China, which would effectively match the tariffs Beijing puts on U.S. imports. The plans are so far unspecified, though Trump said “we’re going to be doing a lot of that.”

China’s foreign minister Wang Yi responded to Trump’s announcement by saying China would make a “justified and necessary response” if the U.S. engaged in a trade war, but added that a conflict would be bad for both parties.

In 2017, China saw a record goods surplus with the U.S. of $375.2 billion. 

Tesla has been a major presence in China’s automobile industry for years. The company sold $1 billion of electric cars in China in 2016, and today it accounts for about 9 percent of China’s electric vehicle market. But Tesla’s growth in the country has been slowed a couple main factors: that “tenfold [tariff] difference” Musk tweeted about, and Chinese laws requiring foreign automakers to partner with domestic companies.