President Donald Trump said Thursday the U.S. could soon impose tariffs on more than $500 billion in Chinese imports, about the amount of total goods the U.S. imported from China last year.

Trump made his comments hours before fresh tariffs on $34 billion of Chinese imports took effect at 12:01 a.m. Eastern Time Friday.

Speaking to reporters on Air Force One on his way to a rally in Montana, Trump gave a running total of what he will seek, assuming China responds with retaliatory tariffs, starting with the $34 billion in levies that kicked in Friday.

“Then you have another 16 [billion] in two weeks and then as you know we have 200 billion in abeyance and then after the 200 billion we have 300 billion in abeyance. OK? So we have 50 plus 200 plus almost 300,” he said, according to reports by Reuters and CNBC, adding “It’s only on China.”

A massive escalation like that would likely rattle financial markets worldwide, and could have costly repercussions for U.S. manufacturers and consumers.

The $34 billion in tariffs are the first part of levies on a total of $50 billion of Chinese goods that Trump announced in June. The second part, with tariffs on $16 billion in Chinese imports, is scheduled to take effect in two weeks.

China has warned it will retaliate in kind. On Friday, there was at first some confusion about whether its countermeasures had been launched immediately after the U.S. move as promised, with conflicting reports coming out of China. But in a briefing Friday, Foreign Ministry Spokesman Lu Kang reportedly confirmed China’s retaliatory tariffs had been implemented, without giving details. A report in state-run news outlet Xinhua indicated they are to the amount of $34 billion and on the range of U.S. goods already outlined.