In its latest crackdown, the Chinese government targeted two more U.S. citizens over "internet rumors," but gave no indication as to whether the latest incidents involved China's new "red alert" over foreign media coverage of the protests in Tiananmen Square, which was commemorated on Monday, exactly 30 years since the crackdown took place. The Global Times, a newspaper associated with China's ruling Communist Party, reported on its Weibo microblog that the two U.S. citizens are being held and prevented from contacting their families. However, the individuals were not said to be under investigation or facing criminal charges. An American missionary, Bob Fu, who runs the Christian Chinese Outreach (CCO) in China, was previously imprisoned in October over similar charges. "Bob was arrested last night. And his family couldn't get him out. He was sentenced to three months in the detention center," Wu'er Kaixi, a member of a Chinese rights group, told Radio Free Asia. "I saw Bob tonight, and the situation is very grim for him. He told me, 'I'll die in China. I will not go back to America,'" he added. Fu, the CCO's director in China, ran afoul of Chinese authorities for posting in Weibo on Monday that Chinese authorities and foreign "puppets" were attempting to "fabricate propaganda" to mark the anniversary of the June 4th crackdown, according to Radio Free Asia. Radio Free Asia also reported that a man identified by his name as "John" has been detained in Beijing for spreading "propaganda" about the anniversary of the Tiananmen protests, according to Wu'er Kaixi. China's "red alert" has targeted various types of foreign media coverage, including a recent report on China's "Great Firewall," which was reportedly cited by police in Chengdu as one of the reasons that officers were seeking to arrest eight individuals on suspicion of "inciting ethnic hatred." In one recent incident in the eastern province of Zhejiang, the U.S. Consulate General in Shanghai informed a 27-year-old U.S. citizen that authorities in the city of Lishui planned to arrest him for "falsely reporting" that people had been rounded up in his city, Radio Free Asia reported. "He was informed by the local police that the authorities are very angry about the report he made in the U.S. Consulate’s WeChat account about a new round-up in Lishui," the radio outlet reported. Last week, Chinese authorities threatened to arrest four people for spreading "fabrication" about last year's military parade in Beijing, following a similar warning regarding foreign news outlets that had posted related content. The Communist Party is often concerned about coverage of the military and the government and reportedly has used its "Great Firewall" to block content related to the crackdown on the 1989 democracy protests. Over the past two decades, the Chinese government has blocked access to a number of social media and online services, including Facebook, Twitter, Instagram and Google, according to Radio Free Asia, as well as numerous websites, including those related to the Tiananmen protests. However, since President Xi Jinping came to power in 2012, the government has become increasingly concerned with the spread of information online. In May, a human rights group in China launched a major censorship awareness campaign, according to Radio Free Asia. "During the last two decades, censorship and surveillance by the authorities, in the name of patriotism and stability, have never been as effective or as comprehensive as they are today," the human rights group PEN America, which published a report titled "The Battle for China’s Ideas," wrote on its website. At a conference last month on government censorship in China, participants called for an increase in Internet transparency. "The fact that China has been blocked for more than 15 years is an expression of its status as a model of censorship. No one likes being blocked," Sun Liping, head of the human rights group PEN International, told the Associated Press. Follow NBC Asian America on Facebook, Twitter, Instagram, and Tumblr.