Donald J. Trump went on the air this morning to offer the stricken nation his deep condolences over the latest school massacre that killed 17 people in Parkland, Fla.

The president offered on behalf of the nation his love and support for the victims and their families. Their grief is borne by the entire nation, he said. “We are one American family,” said the president.

He spoke also correctly about the need to address mental health issues. The gunman who opened fire at the high school had been expelled from the school for disciplinary reasons. He reportedly had exhibited some warning signs that went unheeded by those who know him.

Indeed, we do need to heed these signs. We mustn’t let them go.

Trump also spoke to the compelling need to boost school safety. That, too, is important. As the president noted, parents must not worry about the safety of their children “when they kiss them goodbye” each morning.

School safety. Mental health. Those are valid and important issues.

The president, though, left one critical issue unaddressed this morning. He didn’t mention gun violence. He didn’t speak at all to the need to find ways to keep guns out of the hands of those who exhibit the warning signs that the alleged gunman reportedly did.

Trump vowed to take on the “difficult issue of mental health.” Fine. What about gun violence, Mr. President? When in the name of political sanity are our elected leaders going to take on that “difficult issue”?

I continue to believe there are ways to toughen requirements for legal firearms purchases without impeding Second Amendment guarantees that citizens have the right to “keep and bear arms.”

That, too, needs a nation’s attention. If only the president had started that discussion today.