Within the territorial boundaries of the United States, Donald Trump would squirm in a legislative and judicial straightjacket. He could not defy the Constitution or the Bill of Rights, he could not spend money Congress didn't authorize. If he broke the law he could be impeached.
At America's borders and beyond, however, it's a radically different story, according to the Brookings Institute's Thomas Wright:
The president enjoys his or her greatest power in foreign policy. His power to use force is well known. As important, though, is what he can choose not to do. He can unilaterally refuse to defend an ally. He can choose to strike a bargain with Russia instead of deterring it. He can pull out of a trade deal. There are fewer checks and balances. Damage done in one year may never be undone.
A Trump administration would pose the greatest shock to international peace and stability since the 1930s. This is not because Mr. Trump would invade other countries but because he would unilaterally liquidate the liberal international order that presidents have built and defended since Franklin Delano Roosevelt. If the word “isolationist” has any meaning, he qualifies as one.
Mr. Trump has a coherent and consistent worldview that dates back almost 30 years when he spent $95,000 on a full-page advertisement in the New York Times to publish an open letter to the American people on U.S. foreign policy. It was this worldview that he described to the Washington Post editorial board on Monday. It appears in virtually every interview and speech he has given about world affairs since the 1980s.
Simply put, Mr. Trump thinks America’s allies and partners are ripping it off and he wants out of America’s leadership role in the international order. Over and over again, Mr. Trump has questioned why the Unites States. defends Japan, South Korea, Germany and other nations without being paid for it. Just this week, he promised to significantly diminish U.S. involvement in NATO and when asked if America “gained anything” from having bases in east Asia he replied “personally I don’t think so”. This is not about a more equitable share of the burden, which many have called for. Mr. Trump believes that the U.S. gains little from having allies unless it is paid handsomely paid by them.
As he shuns America’s allies, Mr. Trump would seek to strike deals with Vladimir Putin, president of Russia, and other authoritarian strong men. Mr. Trump has received Mr. Putin’s endorsement and has called for much better relations with Russia.
Meanwhile, to deal with threats to the American homeland, Mr. Trump has promised his own Chechnya-style scorched-earth policy of targeting civilians and using torture.
Some think that Mr. Trump will moderate these positions if he is elected, but it is unlikely that a 70-year old who has held these views for decades and probably views himself as a prophet will abandon them at exactly the moment he feels vindicated and empowered.
A megalomaniac with the world's largest military and a huge nuclear arsenal. What could possibly go wrong? Suffice to say Trump even has the august Brookings Institute worried, very worried.