Tensions escalated and on 14 July 1969, the Salvadoran army invaded Honduras. The Organization of American States (OAS) negotiated a cease-fire which took effect on 20 July and brought about a withdrawal of Salvadoran troops in early August. Contributing factors to the conflict were a boundary dispute and the presence of thousands of Salvadorans living in Honduras illegally. After the week-long war, as many as 130,000 Salvadoran immigrants were expelled.