Final answer:
Nontariff barriers are measures other than tariffs that countries use to limit imports and protect domestic industries, which include quotas, technical standards, domestic subsidies, and currency manipulation, but not an increase in import duties.
Step-by-step explanation:
The characteristics of nontariff barriers that a country may use to protect its domestic industries do not include an increase in import duties, as those are considered tariffs. Instead, nontariff barriers involve measures such as quotas on imports, technical standards and regulations designed to make it more difficult or expensive for foreign products to enter the domestic market, subsidies for domestic producers to reduce their costs and make them more competitive against imports, and various forms of currency manipulation which can affect the price of imports and exports without imposing direct taxes or duties.
For instance, technical standards can limit imports by requiring that products meet certain safety or quality criteria. Rules-of-origin regulations, which dictate where a product was substantially transformed, are another example of a nontariff barrier, as they can influence the final labeling and potentially the import eligibility of a product.