When a war is taking place in a country, it is likely that the exporting and importing activities of the nations involved would decline. This is because many factors necessary for trade would be disrupted.
It is likely that there would be a shortage of workers, as many people will likely be fighting in the war. This would mean that factories and other industries would not be able to produce the products to export. Moreover, money might be redirected towards funding the war, which would make it difficult to import products. Finally, in order for trade to take place, safe transportation needs to be available, and this is unlikely to exist during a war.