Operation Lalang (Weeding Operation; also referred to as Ops Lalang) was carried out on October 27, 1987 by the Malaysian police to prevent the occurrence of racial riots due to the provocation by the ruling government towards DAP. The operation saw the arrest of 106 persons under the Internal Security Act (ISA) and the revoking of the publishing licenses of two dailies, The Star and the Sin Chew Jit Poh and two weeklies, The Sunday Star and Watan.
The political developments which brought this second largest ISA swoop in Malaysian history since the May 13 riots, were sparked ostensibly by mounting political tensions having strong racial overtones. According to the White Paper explaining the arrests, various groups who had played up "sensitive issues" and thus created "racial tension" in the country had exploited the government's "liberal" and "tolerant" attitude, according to the document. This racial tension made the arrests "necessary" and further forced the government to act "swiftly and firmly" to contain the situation, according to some individual's opinions.
Vernacular Chinese school personnel controversy
The sensitive issues were brought on by what appeared innocuously enough as concerns over the Ministry of Education's appointments of some 100 senior assistants and principals to vernacular Chinese schools (Chinese-medium primary schools which the government provides funding and personnel as well as setting the school curriculum, while school assets belong to local Chinese communities represented by boards of trustees). It was learnt that those appointed were Chinese who were not Chinese-educated, implying that students and parents might be forced to use English or Malay to communicate with the school personnel. Chinese educationalist groups contended that the move would limit the usage of Chinese in the schools.
On October 11, 1987, a 2,000-strong gathering was held by the United Chinese School Committees Association of Malaysia (UCSCAM, the association of Chinese school teachers and trustees, also known as Dong Jiao Zong) at the Hainanese Association Building, beside the Thean Hou Temple in Kuala Lumpur, which was joined by politicians from the Malaysian Chinese Association (MCA), the Democratic Action Party (DAP), GERAKAN and other Chinese-based parties. Racially provocative speeches was evoked from the Chinese politicians present. The meeting resolved to call a three-day boycott in Chinese schools if the government did not settle the appointments issue. The boycott was called off later, albeit at the eleventh hour.
Response by UMNO Youth and detentions
In the event, even though the boycott was cancelled, the stage was set for a mirror response from the Malays, led by UMNO Youth. A mass rally of 10,000 was held at the TPCA Stadium in Kuala Lumpur and, by then, UMNO politicians had begun to condemn MCA leaders (both UMNO and MCA are component parties of the ruling Barisan Nasional coalition) for their collusion with the Dong Jiao Zong and the opposition DAP. Amidst calls from both sides for the resignations of MCA Deputy President and Labour Minister Lee Kim Sai and UMNO Education Minister Anwar Ibrahim, UMNO announced the holding of a mammoth rally in KL to celebrate its 41st Anniversary, which it was claimed would see the attendance of half a million members.
The proposed UMNO rally was the ostensible reason for the Inspector General of Police to precipitate the 27 October crackdown. Had the rally been held it was not improbable that racial riots could be sparked by the incendiary speeches of UMNO politicians. To make matters worse, a tinder box situation was already created by the rampage of a Malay soldier who killed a Malay and two Chinese with an M16 rifle in the Chow Kit area, straddling two large Chinese and Malay communities.
Najib Tun Razak, then chairman of the UMNO Youth wing, had led a massive Malay rally in Kampung Baru, Kuala Lumpur. During the rally, Najib was purported seen threatening to bathe a keris in Chinese blood causing the Chinese community to be gripped with fear of the possibility of May 13 repeating. This caused many Chinese businesses around the city was closed for a few days to avoid any potential attacks from the Malay ultra-nationalists.   
The pundits have it that the Prime Minister had to have a quid pro quo for cancelling the UMNO rally. Hence the arrests of prominent Chinese politicians.
Operation Lalang resulted in the arrest of 106 people under the Internal Security Act.  Among the more prominent detainees were opposition leader and DAP Secretary-General Lim Kit Siang, ALIRAN President Chandra Muzaffar, DAP Deputy Chairman Karpal Singh, MCA Vice President and Perak Chief Chan Kit Chee, PAS Youth Chief Halim Arshat, UMNO MP for Pasir Mas Ibrahim Ali, and UMNO Youth Education Chairman Mohamed Fahmi Ibrahim. Other prominent non-political detainees included Dong Jiao Zong (Chinese Education Associations) Chairman Lim Fong Seng, Publicity Chief of the Civil Rights Committee Kua Kia Soong, and WAO member Irene Xavier. The detainees were kept at the usual place used for ISA detainees, at Kamunting Detention Center.
Although most of the detainees were released either conditionally or unconditionally, 40 were issued detention order of two years. Included were Lim Kit Siang and Karpal Singh plus five other party colleagues, a number of PAS members and many social activists. A categorization of the initially named detainees, numbering 97, gives the following breakdown: political parties: 37; social movements: 23; individuals: 37.
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