Lots of people have left President Trump’s White House. Those departures never seemed likely to have a real impact on policy. Most of them didn’t appear to tell us something larger about what was going on within the administration, beyond it being chaotic. But the resignation on Tuesday of National Economic Council Director Gary Cohn, the top White House economic policy adviser, appears to have direct policy implications — and it could portend other changes in the administration.

Why is Cohn different? Four reasons.

Trump seems to be serious about tariffs — This resignation, unlike the departure of Communications Director Hope Hicks last week, appears to be directly related to a policy decision: Trump is on the verge of implementing tariffs on aluminum and steel imports. This move comes over the strong objections of Cohn, who has been trying to block Trump from making it since the start of the administration. Trump sounded like an economic populist during much of the 2016 campaign, but until now he had largely abandoned that approach while in office. Instead, he had been pursuing a Wall Street-friendly agenda of tax cuts and deregulation shaped in part by Cohn, a former Goldman Sachs executive.

That Cohn resigned suggests that Trump is serious about implementing these tariffs, despite resistance from fellow Republicans and the business community. This is not like Trump talking about supporting gun control, only to backtrack soon after. Trump has long favored new tariffs, appears to be acting on that policy preference and didn’t stop pushing in that direction when his top economic adviser objected so strongly that he quit. Of course, this is Trump, so he could always reverse course, but so far he appears more serious about following through on tariffs than on his other more unconventional views.

Trump is breaking with GOP orthodoxy in a big way — Cohn isn’t the only person who objects to these tariffs. House Speaker Paul Ryan, who usually avoids direct criticism of the president, went public with his opposition to the tariffs. So has Texas Sen. Ted Cruz, who has largely aligned himself on policy with the president since Trump entered office.

If Trump is following through with these tariffs, as Cohn’s resignation suggests, this is one of the most significant instances of the president separating himself from the broader party. Despite all the hubbub, Trump has pursued a pretty typically Republican policy agenda; tariffs would be the first real break.

Trump has dumped one of the “adults in the room— We don’t know exactly how decisions are made in the Trump administration. But people on the outside of the administration have likened Cohn’s role on economic policy to that of Defense Secretary Jim Mattis’s on national security — an administration official with more traditional, establishment views looking to push the president away from his more unorthodox instincts. That role helps explain why the presence of Cohn in the White House has been a key source of reassurance to Wall Street and other market-minded constituencies. If Trump is willing to part with Cohn, is the president more likely to take other controversial steps on economic policy that he has hinted at in the past, such as pulling the U.S. out of NAFTA? Also, what if Trump no longer wants advisers who are in conflict with his views? Would he let Mattis resign if the two strongly disagreed on something?

People with good jobs are leaving the White House, suggesting deep staff dissatisfaction — I assume that working with Trump is difficult. That said, there are some major perks. You might, as Hicks did, get to meet the pope. Cohn played a key role in writing a major tax bill. Former President Barack Obama’s economic policy directors all remained for at least 23 months. Cohn is leaving this prestigious job after only about a year. That two fairly senior advisers are departing the Trump administration in a week’s time — whatever the circumstances — is telling. Both Cohn and Hicks appear to have decided that the upside of remaining in the White House is outweighed by the downside.

Does that tell us anything? Maybe not. Every departure has its own peculiarities. Maybe Trump really wanted one or both of them gone, even if these moves were cast as resignations, not dismissals. But at the very least, Cohn and Hicks’ decisions suggest that Trump hasn’t become easier to manage or less erratic. Maybe Hicks and Cohn believe that the best days of working in the Trump White House have passed.

As I said before, this is Donald Trump, so he could decide next week to drop the tariffs idea and hire another person from Goldman Sachs to replace Cohn — or even ask Cohn himself to come back. But I doubt it. Instead, I will be curious — with Cohn ostensibly leaving over tariffs — whether Trump will take additional steps to implement his vision in his second year as president, even if he has to dump some well-respected aides along the way.