Trump leaving WH

U.S. President Donald Trump departs the White House en route to Joint Base Andrews on Tuesday, Sept. 26, 2017 in Washington, D.C. (Olivier Douliery/Abaca Press/TNS)

Donald Trump’s 2016 run for president was built on promises to change business as usual. If it meant anything, Make America Great Again was a populist pledge asserting U.S. dominance over the world regardless of whether other nations liked it or not.

Trump, the well-known dealmaker, would put his skills to work.

Trump vowed a wall along the U.S.-Mexico border would be constructed, and the Mexican government would pay for it.

Trump vowed he would remove the United States from the Trans-Pacific Partnership, a trade agreement among Pacific nations seen as a check on China’s economic dominance.

Trump vowed he would scuttle the North American Free Trade Agreement (NAFTA) between the United States, Mexico and Canada.

Trump vowed he would end U.S. involvement in an international effort to battle climate change, the Paris Agreement on Climate Change.

Trump vowed that unless other NATO members paid what he deemed a fair share, he would withhold U.S. activities related to the global security compact.

Trump vowed he would pull the United States out of the multinational agreement to halt Iran’s nuclear weapons program.

President Trump has yet to make good on all those campaign promises, but his batting average is pretty decent. He has successfully pulled the plug on U.S. involvement in the Trans-Pacific Partnership and the climate change agreement.

Last week, he announced his administration was pulling out of the Iran nuclear deal. “This was a horrible one-sided deal that should have never, ever been made,” Trump said. “It didn’t bring calm, it didn’t bring peace, and it never will.”

What comes next in our attempts to limit China’s economic impact across the Pacific? That’s uncertain.

What comes next in the world’s attempt to prepare for the worst effects of climate change? That’s uncertain.

What comes next in the effort to put a lid on Iran’s nuclear ambitions? Other than the reinstatement of economic sanctions against Iran, that’s uncertain.

“I would advise Iran not to start their nuclear program,” Trump said last week.

This perilous and purely self-inflicted diplomatic confusion calls to mind a warning sent by scores of former U.S. diplomats who had served Republican and Democratic presidents. A 2016 letter signed by these former diplomats warned that Trump “is ignorant of the complex nature of the challenges facing our country, from Russia to China to ISIS to nuclear proliferation to refugees to drugs, but he has expressed no interest in being educated.”

Yet, the nation’s voters rejected those warnings. It’s clear that Trump’s supporters did — and still do — prefer a president who will shake up the old ways of U.S. trade and diplomacy.

What the world will look like if the old alliances formed during the Cold War end is one more uncertainty.