True, Germany sought to use unlimited submarine warfare to stall supplies going into Britain and France, effectively starving Britain and putting a strain to the amount of supplies they have (of course, the US had was big industrial power, and just built more ships for Britain). Germany decided that they had too defeat France & Britain as quickly as possible, then move all their troops to the east to defeat Russia, and then defend against a possible US invasion. Of course it didn't happen that way, as the war with Russia started too soon (not when they wanted), and hundreds of thousands of troops were tied down fighting the Russians instead of being used to crush the Western Front.
hope this helps