Open sources indicate that Russia had far more than 150,000 additional troops under arms for the Ukraine war by the end of 2023, so Sacks’ prediction that they would reach roughly that scale is directionally correct (if anything, conservative).

Key points:

1. Partial mobilization before 2023 already added 300,000 reservists. Putin’s September 2022 decree mobilized about 300,000 reservists for the war.(the-independent.com) Those men were in addition to Russia’s pre‑war active-duty force and were explicitly called up for the Ukraine campaign.

2. Russia then reported hundreds of thousands of new contract recruits in 2023. At his year‑end press conference on December 14, 2023, Putin said that 486,000 people had signed contracts with the armed forces in 2023 and that there were **617,000 Russian personnel in the “combat zone.”(themoscowtimes.com) Independent outlet Meduza, citing the Defense Ministry, likewise reported over 640,000 contract soldiers in the army by late December 2023 and repeated the figure of **486,000 volunteers signed up in 2023.(meduza.io)

3. Even critical analyses still imply additions well above 150,000. RealClearDefense notes that some of the official recruitment figures are likely inflated or double‑count certain contract renewals, but concludes that the true number of people who actually signed contracts in 2023 is still “several times lower than 490,000,” not an order of magnitude lower. Even if one takes a very skeptical view—say, only ~150,000–200,000 net new contracts—that still meets or slightly exceeds Sacks’ 150,000‑extra‑troops benchmark.(realcleardefense.com)

4. Total active-force growth is consistent with a ~150,000+ net increase. A 2025 U.S. Senate assessment, using NATO‑linked data, estimates Russia’s active armed forces at about 1,134,000 troops in early 2025, up from ~900,000 pre‑war—a net increase of roughly 234,000. This is consistent with Russia having added on the order of hundreds of thousands of personnel for the war by late 2023, and therefore at least 150,000.(congress.gov)

Given that all plausible counts of Russian wartime force generation by end‑2023 are at or well above 150,000 additional troops, Sacks’ prediction that Russia would have on the order of 150,000 extra men under arms for the Ukraine conflict by the end of 2023 is substantively correct, though actual numbers appear significantly higher than he suggested.