Why is it so important for weaker countries to keep germany in the nato and european union?

Germany, the largest economy in the European Union, has come in for particular criticism for its relatively cautious defence budget, and as Angela Merkel pays her first visit to President Trump on Friday, many will be looking to see whether the Chancellor will convince her main ally that leading European nations are serious about paying their fair share. For some time, American government officials, defence secretaries and even presidents have accused Europe of “free riding” on the United States for their security.