It's time to focus laserlike attention on the meaning of a Donald Trump presidency for America's security.

Until now, the presumption that Trump wouldn't win or doesn't really mean what he says has led to insufficient scrutiny of how his presidency would threaten our safety. Many security experts - including leading Republicans - have raised concerns, but their protests haven't risen to the level of the danger.

The time for such complacency is past. The Donald brags he will make America "great again," but the policies he promotes would do exactly the opposite: emboldening our enemies, undercutting our allies, and destroying America's clout in the world.

So let us imagine what America's security situation could look like in 2020, after one term of Trump as our commander-in-chief.

Europe: Our most important political alliance, with Europe's democracies, lies in tatters, after Trump's "America First" policy accelerated the breakup of the European Union and the demise of NATO.

Trump tipped his hand in 2016 with an astonishing campaign appearance - in Mississippi - alongside Nigel Farage, the former leader of England's far-right Independence Party, who led a successful campaign for Britain to "Brexit" the EU. As president, Trump openly supported Europe's other far-right (and racist) parties as they worked to destroy the political union that kept Western Europe stable for decades.

Having also declared his disdain for NATO, our closest military alliance, Trump closed down our bases in Germany and England (as well as in Japan and South Korea). He had claimed during the campaign that our allies didn't pay enough for our protection, telling CNN that the benefit of those alliances was "not big enough to bankrupt and destroy the United States."

In reality, our Asian allies paid a huge chunk of the base costs in their countries, while NATO allies paid lesser amounts. But the savings of relocating bases from Europe to America were minimal, since Trump didn't want to disband the transferred military units. What the Donald also refused to consider was the importance of those bases in deterring Russia from undercutting Western democracies (and China from doing likewise in Asia).

By 2020, Russia has become the dominant influence in Europe, nibbling at the Baltics and Poland and annexing half of Ukraine. Moscow continues to fund far-right European parties that support the Kremlin's anti-American policies and its vision of authoritarian "democracy."

This doesn't disturb President Trump, who has finally achieved his decade-long dream of building a Trump tower in Moscow and has regular dinners with his buddy Vladimir Putin. The Donald now hosts a reality show on the Kremlin's global mouthpiece RT (Russian Television), which had already started interviewing Trump during the 2016 election season and offered Farage his own TV show the same year.

Asia: After Trump withdrew America's forward Asian bases, China became the dominant player in Asia, taking firm control of many disputed islands and controlling the sea-lanes. Deprived of the U.S. nuclear umbrella, Japan and South Korea have built nuclear weapons - which Trump said in the 2016 campaign was fine by him.

The nuclear arms race in Asia grows ever more dangerous and could threaten U.S. territory, but Trump's "America First" policy eliminated the nation's critical role as a stabilizer. Meantime, U.S.-China enmity has soared as Trump kept his promise to slap huge tariffs on Beijing, starting a trade war that has cost America millions of jobs.

The Middle East: Iran has gone nuclear. Soon after taking office, Trump kept his pledge to destroy the international treaty that had blocked any Iranian nuclear weapons for at least a decade, leaving Tehran free to race right up to breakout capacity. Trump wouldn't bomb Tehran - he belatedly realized the cost of another Mideast war was too high, and Israel hesitated to go solo. America's Gulf allies, realizing Trump had abandoned them, turned to Moscow for protection.

Terror: Islamic terrorism has risen exponentially in the West and in Israel, as intelligence cooperation has splintered within Europe and among former NATO allies. Trump's responses are to (1) try muzzling U.S. media criticism, after asking Putin for pointers, and (2) blaming everything on illegal immigrants, or other internal "traitors." (However, he has been unable to deport the 11 million or get an outraged Mexico to pay for a wall.)

U.S. standing: Global respect and admiration for America have tanked, as Trump insults former friends and praises its adversaries. Nations no longer look to the United States as a global leader - or a democratic role model. Americans are less safe, but Washington has decreasing leverage to protect them.

I've given you the optimistic prediction. There's no telling what military disasters could be triggered by Trump's temper or his erratic behavior. The risk is too great and the security threat too huge, dwarfing any of Hillary Clinton's flaws. For anyone still sitting on the fence in this election, the time to face up to the danger is now.