South Korea posted a trade surplus for the 21st straight month in October as exports remained strong amid slowing import growth, the customs office said Tuesday. The nation\'s trade surplus came to about US$4.1 billion in October, up from $1.3 billion a month earlier, according to data by the Korea Customs Service. During the January-October period, its cumulative trade surplus reached $25.9 billion. Exports totaled $46.8 billion, up from $46.5 billion in September, while imports declined from $45.3 billion to $42.8 billion over the same period, the data showed. The export growth was driven by robust sales of petroleum products, vehicles and steel, which expanded 31.1 percent, 16.9 percent and 16.2 percent on-year, respectively, the data showed. Exports to China jumped 14.6 percent to $11.86 billion. Shipments to Japan grew 24.7 percent on-year to $3.33 billion, while those to the European Union fell 20.3 percent to $3.95 billion over the same period, according to the data.