Last week, President Trump named Richard Grenell acting director of national intelligence (DNI), replacing Joseph Maguire as the nation’s spy chief. The move seemed to solve several problems for the president. Trump wanted Maguire gone, reportedly furious that Shelby Pierson, Maguire’s top deputy for election threat intelligence, told lawmakers that Russia would prefer to see the president reelected.

Grenell, a fierce Trump loyalist and former Fox News contributor, has been U.S. ambassador to Germany since May 2018. Now he will share that job with the DNI position, which he is expected to hold for 90 days or so. As DNI, Grenell gives the president another highly placed ally to help throttle embarrassing investigations and “clean house” by removing intelligence staff perceived to be disloyal to the president.

Appointing Grenell also relieves pressure on the White House to nominate a permanent DNI. Legally, Maguire could serve in the acting position only until March 11. Naming a new acting DNI allows Trump more time to find a nominee who is loyal but who also has an impressive enough résumé to survive Senate confirmation.

Among the U.S. national security establishment, the response to Grenell’s appointment has ranged from lukewarm to hostile. Some analysts have openly wondered if Grenell will destroy the intelligence community.

Why did this personnel shift happen — and how much does it matter?

Trump wanted a close ally in this role

The simplest answer to this question is also the most accurate: This happened because the president wanted it to happen. But the appointment is not just another example of what scholars call the imperial presidency. Presidents always have had a heavy influence on the intelligence community, and for good reason — the primary consumers of intelligence work sit among the government’s roughly 4,000 presidential appointees. Even Sen. Frank Church (D-Idaho), who famously called the CIA a “rogue elephant” following Cold War-era abuses, later conceded that almost all of these activities had been conducted under presidential direction and approval.

Grenell is not the first head of intelligence appointed with politics in mind. President Richard Nixon, for instance, made James Schlesinger director of central intelligence (DCI) to shake up a CIA he felt had cost him the 1960 election and was continuing to undermine his policies. President Ronald Reagan chose William Casey, his former presidential campaign manager, as DCI — a role that included oversight of the broader intelligence community. (Many analysts believed Casey was involved in the Iran-contra affair, although he died before he could testify about his role.)

Acting DNIs have a limited term

Trump also faced legal pressures to name a new DNI, as Maguire needed to be replaced before March 12. Under the Federal Vacancies Reform Act of 1998, the president can appoint officers directly to positions normally requiring Senate confirmation — but for no more than 210 days. After this period, the acting officer must be replaced unless the president formally nominates someone to the position and submits that name to the Senate. Maguire was appointed acting DNI on Aug. 16, so the fallout from Pierson’s testimony pushed him out only a few weeks early.

But if the president wanted to replace Maguire, why not simply nominate a full-time DNI? Even in a Republican-controlled Senate, confirming a new DNI will be no small feat. Trump’s last proposed DNI nominee, Rep. John Ratcliffe (R-Tex.), withdrew his name from consideration when the media criticized his partisanship and limited intelligence experience and Republican senators indicated their lack of support.

What will Grenell be able to accomplish?

In the short term, Grenell will have influence over a number of ongoing initiatives, such as protecting the 2020 election from interference and working through details of the recently announced U.S.-Taliban deal in Afghanistan.

If Grenell really plans to stay on as ambassador to Germany while serving as DNI, it’s not clear how much time he will have to devote to hands-on management of intelligence matters. What time he does spend seems likely to be focused on promoting the president’s political and policy goals, rather than shaping the way the White House uses intelligence analysis for policy decisions.

This is in part because the intelligence community’s support for policymaking is not as important in the Trump administration as it has been in the past. Trump has long distrusted the intelligence community and has made it no secret that he prefers loyalists to truth-tellers.

The longer-term effects of Grenell’s tenure are harder to predict. Government bureaucracies tend to be resilient, and Grenell is hardly the first Trump loyalist to take over an agency whose work depends on political independence.

At the Consumer Financial Protection Bureau, many believed that the appointments of former Trump budget officials Mick Mulvaney and Kathy Kraninger would decimate the banking watchdog. This hasn’t happened — the CFPB continues to issue and enforce regulations and, just last week, Kraninger requested increased CFPB funding even as the White House budget proposed cuts.

Of course, sustained mistreatment and politicization can have lasting effects. For example, the Trump White House has spent three years gutting the State Department through neglect and aspersion. This makes Trump’s plans for the DNI position all the more important.

The president has indicated that he will nominate a permanent DNI soon and says he has four unnamed individuals in mind for the job. One possible choice, Rep. Douglas A. Collins (R-Ga.), already has said he’s not interested. Once the White House presents a permanent DNI nominee to the Senate, a new round of debates about the role of national intelligence will begin.

Grenell’s tenure, which promises to bring the president’s unique approach to governing more deeply into U.S. intelligence operations, will no doubt color the debate. The harshest critics of Grenell’s appointment, such as John Brennan and William McRaven, are not wrong about the damage Trump has done to U.S. intelligence. But this choice is just the latest salvo in a long campaign to subvert intelligence independence, and bigger battles may be coming.

Brent Durbin is associate professor of government at Smith College and author of “The CIA and the Politics of U.S. Intelligence Reform” (Cambridge University Press, 2017). He is co-director of Bridging the Gap and a 2019-2020 fellow at the Berggruen Institute.