23 February 1981
The regular cross border raids by South African troops, that violated the sovereignty of its neighbouring countries in order to prop up the Apartheid system, resulted in strong condemnation by international governments authorities. This was particularly loud in cases in which South Africa violated the sovereignty of its neighboring countries in order to prop up the Apartheid system. In January 1981, South African forces launched a raid into Matolo, in neighboring Mozambique in order to eliminate ANC personnel based there. This raid led to 23 people being killed, including four South Afrian soldiers taking part in the raid. After the Matolo raid, the Soviet Union an ally of Mozambique sent two warships to Maputo as a sign of its commitment to the country. South Africa's Prime Minister, PW Botha, counting on the support of the West and in particular the United States, issued a statement on the 23 February 1981 indicating that threats by the Soviet Union would not put an end to cross border raids.
References

SANDF,"SA Defence Force involvement in the internal security situation in the Republic of South Africa", from the Department of Justice, [online], Available at justice.gov.za [Accessed: 15 February 2010]|Polity.org.za,"Introduction to regional profiles", from Polity.org.za, [online], Available at polity.org.za [Accessed: 15 February 2010]