Days ago, President Donald Trump threatened Spain with new tariffs unless Madrid increases its defense spending to 5% of its GDP. Whether this tactic proves effective remains to be seen, but one thing is certain: the president has been even more effective than he was in his first term when it comes to getting other nations to honor their commitments. This fact has been most prominent when it comes to defense spending.In 2006, America’s NATO allies agreed to spend 2% of their GDP on defense. After several years of little progress, the Obama administration secured an updated agreement in 2014 that all would achieve this goal by 2024. Yet
