Trump in 2000 said he took a middle ground, supporting a ban on assault weapons though generally opposing gun control.
Trump in 2015, however, was dismissive of calls to regulate assault rifles which, he said,0 are common semi-automatic weapons popular with many Americans.
Now in the wake of the Feb. 14 massacre in Florida that killed 17 high school students and teachers, the nation is again focused on the question of gun control generally and, specifically, of regulating semi-automatic rifles such as the AR-15 allegedly used by the shooter at Stoneman Douglas High School.
Students from the high school who have overnight became outspoken activists for gun control have specifically called on President Trump as well as other elected officials to listen to their concerns and enact gun restrictions.
So where does Trump stand?
Supportive of the US assault weapons ban in 2000
In a page-long explanation of his stance on guns in his book, "The America We Deserve," published in 2000, Trump offered a very generalized summary of Democratic and Republican positions on gun control, characterizing each as extreme.
"Democrats want to confiscate all guns, which is a dumb idea because only the law-abiding citizens would turn in their guns and the bad guys would be the only ones left armed. The Republicans walk to NRA line and refuse even limited restrictions," he wrote.
By contrast, he cast his stance as something of a middle ground.
"I generally oppose gun control, but I support the ban on assault weapons and I also support a slightly longer waiting period to purchase a gun," he wrote.
At the time, the U.S. had a ban on semi-automatic rifles under a law known as the assault weapons ban that took effect in 1994 and expired in 2004.
15 years later, a different view
In his 2015 book "Crippled America," Trump appears to have changed his position.
"Opponents of gun rights often use a lot of scary descriptive phrases when proposing legislative action against various types of weapons. Ban 'assault weapons' they say, or 'military-style weapons,' or 'high-capacity magazines,'" he wrote. "Those all do sound a little ominous, until you understand what they are actually talking about are common, popular semiautomatic rifles and standard magazines that are owned and used by tens of millions of Americans."
In "Crippled America," Trump argues that background checks on prospective gun buyers "accomplished very little" and merely brought "more government regulation into the situation."
Trump cited Project Exile, a crime-reduction program started in Richmond, Virginia, in the late 1990s, which sought to reduce firearms-related offenses by increasing the penalties on felons caught carrying guns. As a presidential candidate, Trump reiterated his support for this program.
'A very big Second Amendment person'
Trump wrote in his 2015 book that he "owns guns. Fortunately, I have never had to use."
According to public records, he got a concealed weapons permit in 2010, which he referred to in an interview with Outdoor Life magazine in early 2016, calling himself "a very big Second Amendment person."
Trump was endorsed by the NRA in May 2016, and the gun rights group ended up spending $30.3 million in support of his candidacy, according to the Center for Responsive Politics.
As president, he has also taken action that may make it easier for some people to get guns, including people with mental illness.
On Feb. 28, 2017, Trump signed H.J. Res. 40, effectively ending a Social Security Administration requirement that the names of people who receive mental health benefits be entered into a database used by the FBI for background checks on prospective buyers of firearms.
The requirement, which had yet to go into effect when Trump ended it, would have added the names of an estimated 75,000 individuals with mental illness to the database, according to the administration of former President Obama. These individuals would have been notified by the Social Security Administration of possible restrictions on their buying firearms, but would have had the opportunity to go through an appeal process.
Since ending the requirement, Trump has pointed to mental health issues as a root cause of a mass shooting in Sutherland Springs, Texas, where 26 people were killed in a church. He has also suggested that mental illness may have been a factor in the massacre at Stoneman Douglas High School in Parkland, Florida, last week.