DA
Dario Amodei (Anthropic CEO)
Author of the essay and architect of the three-part pacing plan; unilaterally committed Anthropic to embedded third-party evaluators.
SA
Sam Altman (OpenAI CEO)
Publicly endorsed the call within hours, matched Anthropic's embedded-evaluator pledge, and separately confirmed OpenAI's IPO delay to at least 2027 citing safety.
Endorsed the call briefly on X ('Dario is right'), signaling rare cross-rival alignment.
DE
Demis Hassabis (Google DeepMind CEO)
Endorsed the direction of the proposal and tied it to DeepMind's own prior industry-standards-body proposal.
DA
David Sacks (White House AI advisor)
Criticized the initiative as regulatory capture that would entrench Anthropic and OpenAI's market dominance while burdening smaller and open-source competitors; urged voluntary action instead of regulation.
ST
Stuart Russell (UC Berkeley AI professor)
Criticized the pacing approach as backwards, arguing safety requirements should gate progress rather than progress buying time for safety.
DA
David Krueger (AI safety professor, former UK AISI director)
Dismissed the plan as insufficient, calling for an immediate indefinite international moratorium on frontier AI development.
JA
Jacob Coxon (former Anthropic/OpenAI researcher)
Resigned days before the essay, warning of extinction-level risk from self-improving AI; his viral resignation entered the same news cycle.
DO
Donald Trump (US President)
Publicly rejected the industry's slowdown calls, prioritizing US-China AI competitiveness over pacing.
CH
China / Chinese government
Named as the hardest coordination partner for the plan's global step; state media reportedly framed the essay critically.