Greta Bossenmaier, the national security adviser to Prime Minister Justin Trudeau who took over the post in the wake of the prime minister's trouble-prone trip to India, is retiring.

Bossenmaier, the former chief of the Communications Security Establishment, began serving as one of Trudeau's most senior advisers on May 23 of last year. She's leaving the public service in December.

"Ms. Bossenmaier has served Canadians with dedication, integrity, and excellence over the past 35 years," Trudeau said in a press statement.

Bossenmaier, who began her public service career as a scientist for National Defence, has held a number of key security-related positions during her career: deputy minister for the Afghanistan Task Force, associate minister in the Department of Foreign Affairs and deputy minister of international development.

A report issued under her authority by CSE in 2017 warned that online attempts to influence or undermine Canada's elections system are becoming more frequent, and great caution should be taken to prepare for such threats before the next federal election.

Bossenmaier replaced Daniel Jean as the PM's national security adviser. Jean is best remembered by Canadians now for his clumsy attempts to explain to reporters how a man convicted of attempted murder managed to get himself invited to two high-profile events with Trudeau, his wife Sophie and senior members of the federal cabinet during a February 2018 trip to India.

Trudeau's current foreign and defence policy adviser, David Morrison, will fill in on a temporary basis in addition to fulfilling his regular duties until a new national security adviser can be appointed.

"On behalf of all Canadians, I wish Ms. Bossenmaier the very best in retirement and thank her for her commitment and dedication during her exceptional career," Trudeau said in the statement.

'A complex and difficult job'

Bossenmaier's retirement after serving as national security and intelligence adviser for one-and-a-half years is not unexpected and likely is connected with the government's post-election transition process, said Thomas Juneau, a former strategic analyst at DND who teaches at the Graduate School of Public and International Affairs at the University of Ottawa.

"Despite comments already popping up on social media, this is a public service job, a non-partisan job," Juneau said.

It's also a complex and difficult job, he said.

"The [national security and intelligence adviser] has limited concrete levers of power. The main one is his or her direct access to the prime minister," Juneau said.

"But compared to the national security adviser in the U.S, she has more limited authority. Even the equivalent in the U.K. has slightly stronger authority."

Bossenmaier served in the role at a time when Canada's threat picture is in flux, particularly given the uncertainty over the status of the Islamic State and the rise of economic national security concerns, said Stephanie Carvin, a former national security official who teaches International Relations at Carleton University in Ottawa.

"Bossenmaier has a reputation for being very professional, and although most Canadians will not be familiar with her name, I also see her as a trailblazer for women working in key national security and intelligence roles," Carvin said.