Why Political issues touch all the international Economy?

Political issues always touch on international economic issues because they are directly related to the interests of the leaders of the State parties involved in international economic matters. For example, lets say State X is rich in resource Y but is currently considering joining a regional economic block that will cause it to trade in Y only in the region. If there is another State Z which wants to buy resource Y but is not within the region of State X, then they cannot trade if X joins the regional block. This change in international trade directly affects the international economy between those2 nations, and possibly with other nations too. Here we see then that the local political considerations of country X will directly affect the international economy