The long-running US debate over gun rights was rekindled after 17 students and educators were killed at Marjory Stoneman Douglas High School in Florida last month.

What happened?

The shooting at Marjory Stoneman Douglas High School has been called the second-deadliest shooting in American history. Investigators said the assault was carried out by 19-year-old former Stoneman Douglas student Nikolas Cruz, who purchased an AR-15-style assault weapon nearly a year ago.

What has the reaction been?

Teenagers across the country have launched a never-before-seen lobbying effort to restrict sales of assault rifles. President Donald Trump said arming teachers and other school staff could help prevent future mass shootings, voicing support for an idea backed by the powerful National Rifle Association (NRA) gun lobby. The governor of Florida, meanwhile, announced plans to require anyone purchasing firearms to be at least 21-years-old, with exceptions for military and law enforcement members. Republican Senator Marco Rubio of Florida said he would support a law that would prevent 18-year-olds from buying a rifle as well as a ban on bump stocks, an accessory that enables a rifle to shoot hundreds of rounds a minute. Last October, a retired real estate investor used multiple assault rifles equipped with bump stocks to kill 58 people at a Las Vegas outdoor concert, the deadliest attack by a single gunman in US history. The NRA opposes an outright ban on bump stocks but has said it would be open to restrictions on them.

Will anything likely change?

The US Constitution protects the right of Americans to bear arms, a measure fiercely defended by Republicans. Even though President Trump has come under pressure to act, any serious move would cause him to alienate parts of his political base, something he has been reluctant to do so far in office.