SafeSteer: Localized On-Policy Distillation for Efficient Safety Alignment

Hao Li, Jingkun An, Zijun Song, Pengyu Zhu, Rui Li, Hao Wang, Wendi Feng, Yesheng Liu, Lijun Li, Jin-Ge Yao, Lei Sha


Abstract
Aligning Large Language Models (LLMs) with human values often degrades their general capabilities, known as the alignment tax. Existing methods mitigate this by balancing dual objectives, which heavily rely on massive general-purpose data or auxiliary reward models.

In this paper, we argue that because safety features are inherently sparse within the output distribution, alignment requires localized modifications rather than global trade-offs. To this end, we propose SafeSteer, which performs on-policy distillation confined to safety tokens. First, we construct a safety teacher via activation steering. Based on this teacher, we develop a safety token selection algorithm. Consequently, SafeSteer restricts the reverse KL penalty to these tokens during training to preserve general capabilities.

Experimental results across diverse models show that our SafeSteer significantly outperforms existing methods on 7 safety benchmarks, with only minimal degradation on 5 general capability benchmarks. Notably, SafeSteer requires only 100 harmful samples without using any general-purpose data, less than 1% of what previous baselines used, considerably reducing alignment cost.
Anthology ID:
2026.emnlp-main.555
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
12729–12747
Language:
URL:
https://aclanthology.org/2026.emnlp-main.555/
DOI:
Bibkey:
Cite (ACL):
Hao Li, Jingkun An, Zijun Song, Pengyu Zhu, Rui Li, Hao Wang, Wendi Feng, Yesheng Liu, Lijun Li, Jin-Ge Yao, and Lei Sha. 2026. SafeSteer: Localized On-Policy Distillation for Efficient Safety Alignment. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 12729–12747, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SafeSteer: Localized On-Policy Distillation for Efficient Safety Alignment (Li et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.555.pdf