The united states often uses sanctions to a country. create an exception on impose a penalty on discourage trade with step into a conflict with

The correct answer is: "impose a penalty on a certain country or group of countries".

Economic and trade sanctions are common mechanisms in international affairs. They are imposed by a country, like the US, and they consist on setting a penalty on imported products from one or more other nations.

Sanctions aim to force the punished nations to change their behaviour or policies on a certain issue, by limiting their ability to trade with the nation or group of nations that has(have) imposed the sanction and, in turn, they negatively influence their economic growth opportunities.

For example, the US imposes a sanction aiming to force a country to respect human rights by abolishing child labor.

the completion of the erie canal spurred the first great westward movement of american settlers, gave access to the rich land and resources west of the appalachians and made new york the preeminent commercial city in the united states.