Diesen has faced extensive and sustained criticism for promoting
Russian propaganda. and for
Ny Tid. He also wrote articles for the
Lowy Institute's
The Interpreter blog from 2016–2017 while he was a lecturer at
Macquarie University. He has a
YouTube channel, on which he has hosted
John Mearsheimer,
Karin Kneissl,
Ron Paul, and
Douglas Macgregor, Diesen has written some op-eds published in
Aftenposten, some co-authored with
Arne Treholt. One 2020 op-ed with Treholt, a convicted KGB agent, stated that Russia has "legitimate interests and security needs" and that Russia was unfairly demonized as a security threat. The article also argues that Norway was becoming the frontline state in the West's war on Russia. The paper's former foreign affairs editor and Moscow correspondent wrote that Diesen and Treholt's article uncritically spread Russian propaganda, and that in postulating that Norway was becoming a frontline state against Russia and China in a militarized Arctic, with the US in the driving seat, they turned things upside down, ignoring large-scale Russian rearmament in the Arctic since 2010, with better equipment on the
Kola Peninsula.
Palm Beach Atlantic University historian Roger Chapman's
H-Net review of Diesen’s 2020 book
The Decay of Western Civilization and Resurgence of Russia describes the book as an ideologically charged defense of
Putin’s Russia (Diesen calls Russia's incursions into neighboring countries as “nation-building initiatives”) and an "incarnation of Russian messianic thinking", which romanticizes
authoritarianism and positions Russia as a cultural savior amidst
Western decline. Chapman argues that Diesen's ideas resonate with those of the
alt-right, noting Diesen’s admiration for figures like
Steve Bannon and his approval of authoritarianism as a “moral virtue.” Russian studies scholar 's ''
review of Russian Conservatism
(2021) criticizes Diesen for blurring the line between scholarly analysis and ideological advocacy, noting that his use of ideologically loaded concepts undermines the book’s academic credibility. As she writes, “Diesen’s book is difficult to read, since it is unclear whether it constitutes a societal analysis or a partisan contribution to the debate on Russia’s future,” adding that he blends “subjective judgments and objective analysis” while presenting conservative assumptions as universal truths. Russian Conservatism'' was described by
The Christians Party leader Erik Selle as the "year’s most important book"; Selle took the term "
national conservativism" from Diesen to describe his own ideology. Diesen’s 2022 book
Russophobia is about
anti-Russian sentiment. It rejects as Russophobic propaganda the accusation that Russia was preparing an invasion of Ukraine; however,
Russia's full invasion of Ukraine took place before the book was published. In a review in the periodical
Vagant,
Russian studies scholar Kåre Johan Mjør argued that the work itself functions as propaganda. Mjør contended that the book employs sweeping generalizations, lacks engagement with relevant academic literature, and selectively cites sources to promote a pro-Kremlin narrative, concluding that the book fails to meet basic standards of scholarly rigor. In a review for
Media, War & Conflict, Chang Zhang and Ting Zhou of the
Communication University of China described the book as an insightful analysis of Russophobia in the
West and its negative implications especially for the latter. They concluded that the book "has arguably drawn a delicate balance between theoretical reflectivity, historical depth and empirical breadth." In Spring 2022, after
Russia's full invasion of Ukraine, Diesen was widely criticised for his regular writing for RT. Diesen states that a significant reason for the 2022 Russian invasion of Ukraine is
NATO's eastward expansion and Russian security concerns regarding
Ukraine membership in the alliance. He believes that the conflict is largely a
proxy war between NATO and Russia over control of the
Black Sea region with Ukraine as the victim of their power struggle. Nonetheless, Diesen believes that the Russian invasion was a serious misjudgment by the country's leadership.
Peace Research Institute Oslo's
Pavel K. Baev, in his review of
The Ukraine War and the Eurasian World Order (2024), describes Diesen’s book as an uncritical academic defense of Putin’s invasion of Ukraine, stating it attempts to justify Russian aggression using “blend of shallow history, vulgar geopolitics and undiluted propaganda.” Baev criticizes Diesen for presenting the war as a positive event, “the graveyard of liberal hegemony”, and for relying on “lengthy quotes from Putin and Xi Jinping” in place of substantive analysis or theoretical grounding.
Geoffrey Roberts praised the book in his review for
The Political Quarterly. Writing that Diesen is a soft realist with the book being "as much about ideas, values and subjectivities as transformations in power structures". Roberts states that "In no way does Diesen justify Putin's action—‘a war of aggression with unpredictable consequences’—but he does try to understand it." Ultimately, according to Roberts, Diesen sees that Western policies in Ukraine will lead to the transition of international relations from that of liberal hegemony dominated by the United States to a
multipolar Eurasian world order. In March 2025, a group of 20 Norwegian academics published an open letter accusing the
Norwegian Helsinki Committee of attempting to curtail Diesen’s
academic freedom. The Committee rejected the allegations as baseless, stating that they had not advocated for any form of censorship or dismissal, but had exercised their own freedom of expression in criticizing Diesen's role in disseminating Russian propaganda. 50 academics and public figures signed a counter-statement in support of the Committee, defending its right to publicly criticize Diesen’s views and methods. They argued that academic freedom must be grounded in truth-seeking and scholarly integrity, and asserted that Diesen "frequently operates well outside of that scope." 37 University of South-Eastern Norway staff also published an open letter condemning Diesen's views. In May 2025, Diesen faced renewed criticism from commentators and researchers who accused him of actively promoting Russian state narratives under the guise of academic analysis. Former minister
Torbjørn Røe Isaksen criticized Diesen’s rhetorical style and misrepresentation of academic sources. Aage Borchgrevink argued that Diesen’s public statements, such as casting doubt on Russian responsibility for the
Bucha massacre, violate basic norms of academic integrity, and called for investigation by his university’s research ethics board. Scholars and
Sven G. Holtsmark criticised Diesen's work for lacking scholarly rigor and promoting an ideological narrative aligned with Russian state propaganda, arguing that his publications rely on selective use of sources, omit crucial context, and fall short of academic standards, replacing analysis with ideological framing. ==Political activism==