Yes, the US should decrease the budget for international affairs, because being involved in foreign affairs only causes trouble. It is important to be polite to other nations, but that does not mean that we need to get involved in their business. Getting tangled in international affairs is costly, as well as risky.
The United States should decrease their budget for international affairs by a slightly marginal amount. The country has enough of its own domestic issues that could use funding, rather than worrying about international affairs that consume a large part of the budget. By taking the money saved from limiting the internal budget, the United States could quickly work on solving its more pressing issues within its homeland, such as its health care crisis and poor economy.