President Donald Trump's call for unity during his State of the Union address was a welcome change from his typically combative, divisive mode. But for such a call to ring genuine, Trump will have to follow with strong actions.

He should not, as he did during the address, issue a barely veiled threat to the Democratic House against "ridiculous partisan investigations" that, incredibly, he said would jeopardize the nation's economy and could spur retaliation. It is Congress' duty to provide oversight and accountability where needed, and Republicans should be prepared to make that a fully bipartisan effort.

If the president truly wants to unify the country, and to operate not as "two parties but one nation," he could have started by acknowledging this winter's searing, costly and needless monthlong partial government shutdown and pledging to work diligently with Congress to avoid a repeat. The temporary funding mechanism that ended the shutdown expires in less than 10 days, and so far Trump has done little but denigrate the negotiations as a waste of time and continue to threaten to declare a national emergency to get the border wall he could not wring from a Republican Congress in the first half of his term.

More beneficial to him and the country would be to follow the model for the recent bipartisan criminal justice reforms that he can claim as a legitimate achievement. A similar template could be used for the comprehensive immigration reforms that have eluded the country for so many years. After having proposed severe limits on legal immigration, Trump doubtless startled many when he reversed himself Tuesday night, saying he wants to see legal immigration "in the largest numbers ever."

Democrats should take him at his word and present a plan built around expanded legal immigration, the return of thousands of detained migrant children to their families, and state-of-the-art border security, in whatever form that takes.

Trump should also have dealt forthrightly with the deficit and national debt that have exploded on his watch, in no small measure because of the irresponsible tax cut he and Republicans pushed through. Cynically, some Republicans have pointed to a slight projected growth in revenue that surfaced in a recent Congressional Budget Office report while failing to note that it comes almost entirely from the expiration of temporary individual income tax cuts used to mollify the masses.

Failure to deal with the debt will leave Trump unable to achieve whatever vision he may have for this country, be it a fortified military, re-­energized space program, the infrastructure goals he set out early and which still are needed, and even the wall whose ultimate price tag has been estimated at more than $25 billion. He instead will leave a legacy of debt and drag on the economy that the next president and Congress will have to clean up.

Similarly, Trump failed to even mention climate change. But his persistent refusal to address it does not alter its toll. His own government's data show mounting costs in the billions and growing loss of life as the nation experiences more episodes of severe weather traceable to a destabilizing climate.

Trump's lookbacks honoring NASA space pioneers, veterans and Holocaust survivors were fine and traditional notes to hit in a State of the Union address. What was missing was a coherent vision for future American greatness that embraces this nation's diversity, lifts its citizens and addresses its challenges head-on instead of fomenting discord with invented crises.