Among withheld retweets in the Turkish dataset, 92% of the corresponding original tweets were also withheld, while 4% survived uncensored and 4% belonged to fully-withheld accounts; this asymmetry suggests the Turkish government's censorship targeting mechanism operates with some degree of systematic (possibly hashtag- or keyword-based) sweep rather than purely manual per-tweet review.

Manual review of 46 fully-withheld Turkish accounts found that 36 (78%) were classified as posting anti-government political content critical of President Erdoğan, 2 as pornography, 1 as advertising bots, 3 as unidentified, and 4 as no-longer-findable; NMF/tf-idf topic modeling of withheld individual tweets confirmed that the dominant censored themes were criticism of government-aligned media and ruling-party politicians.

§6.1, §6.2 evaluation

Twitter's country-withheld content mechanism relies on a browser-set location cookie, not IP geolocation; the authors confirmed that viewing a known-withheld Turkish tweet via a Turkish proxy server did not trigger the withholding display, but manually changing the Twitter app's location setting to 'Turkey' did — meaning any Turkish user who sets their location to a different country can bypass the entire withholding mechanism without Tor or a VPN.

§7 defense

The Chilling Effects database contained only 33 notices from Twitter across all countries, far fewer than the 108 account-withholding requests disclosed in Twitter's own transparency reports for the same period; Twitter itself acknowledges its transparency reporting is neither 100% comprehensive nor complete, and the authors confirmed that at least 86% of Turkish government withholding requests for non-protected tweets were approved by Twitter.

§3.1, §4.2 policy

Twitter's official transparency reports for Turkey recorded 183 withheld tweets (Jan–Jun 2014) and 1,820 withheld tweets (Jul–Dec 2014), but the authors' collection of 17 million geo-bounded Turkish tweets yielded 3,258 withheld tweets from the streaming phase alone, and expanding to followers of censored accounts produced 171,652 withheld tweets—roughly two orders of magnitude more than Twitter's own disclosures.

§4.1, §5.2 evaluation

During the June 2025 shutdown, Iranian authorities blocked international One-Time Password (OTP) SMS delivery, preventing new sign-ins to foreign secure-messaging platforms and VPN services. This forced users toward government-approved domestic platforms that lack security and privacy protections. The blockade of OTPs effectively weaponized account-recovery flows as a secondary shutdown layer, disproportionately affecting users who needed to activate new circumvention tools during the crisis.

2025-iran-shutdown-measurement §Human Rights Implications port-blockingdpikeyword-filtering

Simple character-level perturbations (English) and homophone substitutions (Chinese), combined with LLM instruction-following prompts directing the model to use word substitutions in its output, successfully bypassed all input and output filters for all 41 input-blocked and 197 output-blocked queries across five major Chinese LLM services (Baidu-Chat, DeepSeek, Doubao, Kimi, Qwen). Every input-blocked query contained at least one keyword combination that alone triggered the filter, confirming keyword-matching rather than semantic classification.

2026-ablove-characterizing §VII-D keyword-filtering

Cross-national experiments conducted from Singapore, South Korea, and Taiwan during February 19–24, 2025 found no variance in blocking implementations, event syntax, or server infrastructure across all five Chinese LLM services. Input blocking was enacted identically in all three international locations, and services connected to the exact same server IP addresses globally — Kimi and Baidu-Chat connected to identical IPs and DeepSeek to the same two addresses across all tested locations.

2026-ablove-characterizing §VIII-A keyword-filtering

Input blocking in Chinese LLM services (DeepSeek, Qwen, Kimi, Doubao) is overwhelmingly consistent: all four services persistently block the exact same queries across all 5 measurement samples in both Simplified and Traditional Chinese. Output blocking is far less consistent, with only 29 out of 349 output-blocked queries blocked across all 5 samples. Baidu-Chat is exceptional: it performs almost no input blocking but instead relies heavily on post-search and output blocking (78.6% of blocks are output-phase).

2026-ablove-characterizing §VI-B keyword-filteringdpi

DeepSeek, Kimi, and Doubao all transmit analytics logs to the same Autonomous System (AS24429, Zhejiang Taobao Network Co., Ltd., a ByteDance/Volcengine subsidiary), with one monitoring endpoint IP directly overlapping between DeepSeek and Doubao. Additionally, all four non-Qwen services maintain connections with servers physically located in China throughout the chat session, transmitting user IDs, session IDs, viewport data, language preferences, and in Baidu-Chat's case, the full query text via URL-encoded CAPTCHA requests.

2026-ablove-characterizing §VI-D keyword-filtering

All five Chinese LLM services transmit partial or complete responses to the client machine even when output blocking is triggered, representing a major information leak. For DeepSeek and Qwen, truncated blocked responses are on average close in token length to full successful responses. For Baidu-Chat, the complete response is transmitted to the client but only partially rendered in the browser UI, with only a word or two visible on screen.

2026-ablove-characterizing §VI-C keyword-filtering