The global nature of corporate activity transcends national boundaries under the latest version of capitalism called neoliberalism. Unlike their policies which control the movement of workers across national boundaries, our ruling class has made it easy for the rich and their corporations to move operations across boundaries. Just as US corporations have reduced their labor costs by transferring their operations to low cost labor areas of the world, so have they kept their money in low tax areas of the world. This results in austerity policies within the US and the further hollowing out of the infrastructure. Of course, US government expenses that are never cut are military and largely secret subversive and surveillance agencies like the CIA and NSA to insure the global dominance of the US-led capitalist gang.
Because tax law discourages moving that money back to the U.S., cash is piling up abroad and companies are taking novel steps to adapt, including borrowing against those assets to finance operations at home.Hence, US corporations tend to keep their money out of the country.
.... American multinationals are taxed by the country where profits are earned and by the U.S. when -- or if -- the money is brought back.