Changes of administrations usually mark dicey times in American foreign policy. But transitional hazards will never be greater than in 2016.

Over a span of just a few months in mid-1945, new president Harry Truman lost all trust in Soviet Union strongman Josef Stalin — in a way that Truman’s predecessor, the ailing Franklin Delano Roosevelt, never had during nearly four years of World War II.

Ensuing American foreign policy jerked from a pragmatic Lend-Lease alliance with a duplicitous communist superpower to a tense Cold War.

President John F. Kennedy was young, idealistic, cocky — and without the military reputation of his predecessor, the much more experienced former general Dwight D. Eisenhower. Soon after JFK’s inauguration in 1961, Soviet Premier Nikita Khrushchev predictably began testing Kennedy’s mettle as commander in chief, from Berlin to Cuba.

Kennedy’s eventual restoration of American deterrence during the Cuban blockade marked the scariest phase in Cold War history.

By 1980, as lame duck Jimmy Carter neared the end of his first and only term, the Russians had sought to absorb Afghanistan. Communist insurrections kept spreading in Central America. China went into Vietnam. The new theocracy in Iran still held American diplomats and employees hostages.

Most aggressors had logically accelerated their risk-taking before the newly elected, mostly unknown (but volatile-sounding) Ronald Reagan took office in 1981.

The world’s bullies are now wagering on whether 2016 likewise offers one final opportunity to consolidate their easy recent winnings. Or, in their hubris, might they ramp up their belligerence one last time before the arrival of a new president who will be more likely be supportive of the U.S.-led postwar order?

China, with impunity, has fortified seven newly created artificial islands located in the hotly disputed Spratlys archipelago, a strategic pathway positioned in the heart of the South China Sea. Has China now set a precedent that any nation can build artificial but sovereign islands in the Pacific, replete with automatic territorial claims to surrounding waters?

If so, will Iran or Russia in 2016 create new islands out of thin air in the Persian Gulf, the Mediterranean or the Atlantic? Or will the next president have to warn the Chinese that no nation can in godlike fashion birth permanent fortified islands in the middle of international sea lanes?

Will Beijing seek to push the envelope even more in 2016, fearful that the next president in 2017 — whether Hillary Clinton or a Republican — could be more like Truman or Reagan than Carter or Barack Obama?

Russian President Vladimir Putin has come to expect that his border aggressions do not risk much Western pushback. Will Putin continue to take risks after the departure of Obama, who would rather lecture the Russian leader than stop Russian aggression, more worried about keeping intact his legacy as a Nobel Peace Prize winner than preserving post-Cold War borders?

The Islamic State is only about two years old, but it already has already carved out huge swaths from Syria and Iraq in its dreams of a new Islamic caliphate that will remake the entire Middle East. So far, Western responses have been anemic.

But can the Islamic State afford to gamble that under the next president, 75 percent of U.S. combat missions against ISIS will return to their base without firing a shot or dropping their bombs, as has been the case under the Obama administration? Prepare for stepped-up Islamic State offensives during a last-chance year of the Obama presidency.

Over the last seven years, the world has become acclimatized to the lead-from-behind role of the United States. Under Obama, friends and enemies bet that America was conflicted about the wisdom and morality of the entire American-led postwar global enterprise and reacted accordingly.

But — who knows? — the next American president may identify radical Islam as the catalyst for terrorism directed at the West.

Cuba in 2017 may no longer be seen as a newfound friend but as an old-time violator of human rights.

Next year, will the Islamic State still be seen as a “jayvee” organization, or as an existential danger to the U.S. homeland?

In all of these cases, uncertainty rather than assured continuity in present U.S. foreign policy is likely — largely because the stubborn and tone-deaf Obama administration has lost the support of the American public on almost all of its foreign policy initiatives, from signing the Iran pact, to dealing with terrorism, to handling China and Russia.

Unfortunately, the predictable corrections under a new president in 2017 will make 2016 more dangerous than any year since 1980.

© 2016 TRIBUNE CONTENT AGENCY, LLC.