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President Donald Trump took the first step toward arming America's teachers on Sunday night, promising Justice Department assistance to help fund firearms training for school personnel.

The proposal, which the president announced last month after a former student killed 17 people at Marjory Stoneman Douglas High School in Parkland, Florida, was part of a series of school safety measures the White House released Sunday evening.

It would also seek to bolster firearm background checks, expand mental health programs and encourage military veterans and retired law enforcement officers to take up careers in education. But it doesn't include a proposal the president floated March 1 to raise the minimum legal age to buy semi-automatic weapons from 18 to 21, an idea the National Rifle Association vigorously opposes.

In a pair of tweets Monday morning, Trump touted the highlights of his plan and defended himself for not advancing steps for raising the age limit.

Very strong improvement and strengthening of background checks will be fully backed by White House. Legislation moving forward. Bump Stocks will soon be out. Highly trained expert teachers will be allowed to conceal carry, subject to State Law. Armed guards OK, deterrent!....... — Donald J. Trump (@realDonaldTrump) March 12, 2018

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"On 18 to 21 Age Limits, watching court cases and rulings before acting. States are making this decision. Things are moving rapidly on this, but not much political support (to put it mildly)," Trump said on Twitter.

The proposals are a general outline and include few details on regulatory procedures or funding.

In a conference call with reporters, Education Secretary Betsy DeVos — who said she will head a new commission to study school safety and the "culture of violence" — called the proposals a "pragmatic plan to dramatically increase school safety."

DeVos told NBC's "Today" on Monday that although the White House’s current school safety plan does not raise the minimum age for gun purchases as Trump originally considered, “everything is on the table.”

She added that she didn't think arming every teacher with a gun would be “an appropriate thing.”

“This is an issue that is best decided by local communities and by states,” she said. "The point is that schools should have this tool if they choose to use the tool...but nobody should be mandated to do it."

Andrew Bremberg, director of Trump's Domestic Policy Council, said the commission would solicit ideas from authorities at all levels of government. And he said the White House was encouraging Congress to pass a bill introduced by Sens. John Cornyn, R-Texas, and Chris Murphy, D-Conn., to strengthen the FBI's National Instant Criminal Background Check System, or NICS.

"No stone will be left unturned," Bremberg said.

A senior administration official said on condition of anonymity Sunday that while there was no explicit deadline to implement the program, "we will see responses in under a year."

Rick Cron, a school resource officer with the Shelby County Sheriff's Office, watches students at a school in Sidney, Ohio, on Feb. 26. The district is one of hundreds across the country that have given staff access to guns, seeing the weaponry not as a political statement but a practical response to a potent threat. Andrew Spear / The New York Times via Redux Pictures

The official said DeVos' commission would study the question of raising the minimum age to buy semi-automatic weapons. Asked whether the NRA could still throw roadblocks in the way, the official said, "We are not concerned about NRA."

"They are patriots that love our country, so they want to find ways to help," the official said.

An NBC News|SurveyMonkey poll indicated last week that a majority of Americans disagree with Trump's proposal to arm teachers.