Tough challenge for President Trump tonight in his address to Americans about the nation’s future strategy in Afghanistan. He needs to sound firm, resolute and measured, as he did after the April missile assault on the Syrian airbase that had launched the chemical attack on civilians. Not fire and fury as when the president was intimidating North Korea’s Kim Jung un, successfully for now.

Although he’ll deliver it from nearby Fort Myer, the 9pm ET remarks are, in effect, an Oval Office address, Trump’s first.

Not that Trump seems to care much, but the world will be watching too. It’ll take a stream of steady decisions to mute the wild man portrayed in allies’ foreign media. And remember, Afghanistan combat, now the nation’s longest war ever, is a coalition effort with NATO partners who responded to the 9/11 attack as one on every member.

Potential adversaries will watch to see if Trump’s Afghan strategy is for real or if it’s one of those Obama red-line deals full of words and zero action.

And Americans will seek a coherent explanation for what this new strategy is designed to do and why we need one 5,797 days after President George W. Bush sent troops to destroy the Taliban and its safe havens that planned 9/11.

During the campaign, candidate Trump said U.S. foreign policy had become much too predictable, predictably limp. That’s an inaction that Russia’s Putin took full advantage of in Crimea, Ukraine, Iran and Syria.

Recall earlier this month how intentionally vague Trump was about precisely what awful reaction might await a North Korean provocation. Second parties, says deal-maker Trump, need to be uncertain about your precise intentions. So, Trump may leave blank spaces in his strategy description.

But the commander-in-chief will leave no uncertainty about what he calls his most important job, keeping Americans safe.

Trump has shown a respect for and deference to generals, who are actually military chief executives. Yes, he fired Gen. Mike Flynn, but that involved dishonesty. Think Trump’s national security adviser, (Gen.) H.R. McMaster. Trump’s chief of staff (Gen.) John Kelly. And Trump’s Secretary of Defense (Gen.) James Mattis.

Under President Obama, combatants in Syria, for instance, often had to seek permission all the way back to 1600 Pennsylvania Avenue from Obama aides, who were thinking politics not military. Special Forces ambushing an ISIS caravan, for instance, could not pursue the enemy if they dropped their guns and ran as sudden civilians.

To carry out his vow to crush ISIS, Trump has given free rein to Mattis, the Marine. The secretary has sent decision-making back down to the on-scene colonels and captains, where it belongs. Before the assault, they surrounded Raqqa, for instance. That might make the Raqqa battle more intense briefly, but few enemy will escape to fight another day elsewhere.

Remember, initially Obama said Afghanistan was the important war, not Iraq. Later, Obama became much more interested in withdrawing U.S. troops than winning, a dangerous draw-down to under 10,000 that made protecting each other difficult.

One cringe-worthy stat: Obama was commander-in-chief for 50% of the Afghan war, but 73% of U.S. fatalities. In June, Trump dispatched 4,000 more soldiers to train and assist Afghan forces.

Mattis’ recommendations, discussed at the Camp David meeting Friday, will surely require additional forces. Probably a fair number of Special Ops too. But the total won’t be so many that it looks like a new war or the tedious and precarious nation-building that campaigner Trump denounced — or that tribal Afghanistan is historically unwilling to abide.

Given strains on the rebuilding military depleted during Obama’s years and post-Vietnam wariness over fighting insurgencies on a large-scale, Trump seems unlikely to order a large surge. But, wait. He does take pride in being unpredictable.