Reasoning Structure Matters for Safety Alignment of Reasoning Models

Fuente: arXiv
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Main Authors: In, Yeonjun, Kim, Wonjoong, Park, Sangwu, Park, Chanyoung
Format: Preprint
Published: 2026
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author In, Yeonjun
Kim, Wonjoong
Park, Sangwu
Park, Chanyoung
author_facet In, Yeonjun
Kim, Wonjoong
Park, Sangwu
Park, Chanyoung
contents Large reasoning models (LRMs) achieve strong performance on complex reasoning tasks but often generate harmful responses to malicious user queries. This paper investigates the underlying cause of these safety risks and shows that the issue lies in the reasoning structure itself. Based on this insight, we claim that effective safety alignment can be achieved by altering the reasoning structure. We propose AltTrain, a simple yet effective post training method that explicitly alters the reasoning structure of LRMs. AltTrain is both practical and generalizable, requiring no complex reinforcement learning (RL) training or reward design, only supervised finetuning (SFT) with a lightweight 1K training examples. Experiments across LRM backbones and model sizes demonstrate strong safety alignment, along with robust generalization across reasoning, QA, summarization, and multilingual setting.
format Preprint
id arxiv_https___arxiv_org_abs_2604_18946
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Reasoning Structure Matters for Safety Alignment of Reasoning Models
In, Yeonjun
Kim, Wonjoong
Park, Sangwu
Park, Chanyoung
Artificial Intelligence
Large reasoning models (LRMs) achieve strong performance on complex reasoning tasks but often generate harmful responses to malicious user queries. This paper investigates the underlying cause of these safety risks and shows that the issue lies in the reasoning structure itself. Based on this insight, we claim that effective safety alignment can be achieved by altering the reasoning structure. We propose AltTrain, a simple yet effective post training method that explicitly alters the reasoning structure of LRMs. AltTrain is both practical and generalizable, requiring no complex reinforcement learning (RL) training or reward design, only supervised finetuning (SFT) with a lightweight 1K training examples. Experiments across LRM backbones and model sizes demonstrate strong safety alignment, along with robust generalization across reasoning, QA, summarization, and multilingual setting.
title Reasoning Structure Matters for Safety Alignment of Reasoning Models
topic Artificial Intelligence
url https://arxiv.org/abs/2604.18946