HIS faced etched with the effort of controlling his grief - and perhaps even his anger - Barack Obama used his speech before the shattered people of Newtown to declare he would use all his authority to change the way America protects its citizens from mass shootings.
''In the coming weeks, I'll use whatever power this office holds to engage my fellow citizens, from law enforcement, to mental health professionals, to parents and educators, in an effort aimed at preventing more tragedies like this, because what choice do we have?'' he said. ''We can't accept events like this as routine.''
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'You are not alone': Obama to Newtown
Joining a community in mourning, US President Barack Obama attends a vigil honouring the victims of the violent school shooting in Newtown.
The President did not directly mention guns, nor did he detail what changes he would seek, but his language was remarkably frank, given the sombre circumstances of the interfaith memorial service for Newtown's 26 dead.
''We can't tolerate this any more … These tragedies must end. And to end them, we must change,'' he said.
As the President noted, this was the fourth time he had addressed memorials for victims of mass shootings. But it was the first time in such an address he declared he would pursue reform.
After six people were killed and a congresswoman, Gabby Giffords, was shot in the head in Tucson in January last year, Mr Obama won support across party lines for a speech many considered the finest of his presidency.
In that speech he avoided any mention of policy change, just as in an address after the killing of 12 and wounding of 58 by a gunman armed with another military-style semi-automatic rifle at a cinema in Aurora, Colorado this year, the President emphasised the need to address the broader causes of violence.
He was also careful not to make it an issue during the election campaign, though the subject was raised in the second presidential debate, when he gave some indication of what reform he might pursue. He said: ''Weapons that were designed for soldiers in war theatres don't belong on our streets.''
Hours before he spoke, a senator, Diane Feinstein, who in 1994 introduced laws banning such weapons before Congress allowed the bans to expire in 2004, said she would introduce such a bill on the first day of the new Congress.
''The purpose of this bill,'' she said, ''is to get … weapons of war off the streets of our cities.''
It was the introduction of that ban that made gun control such a terrifying issue for Democrats - 34 incumbents blamed their loss in the 1994 election on their signing of that bill.
Since then many have criticised the ban as being too easy to circumvent. Gun manufacturers simply built new models of the semi-automatic firearms it outlawed and continued selling them.
Other methods of federal gun control could include tightening regulation covering the screening of people seeking to buy them.
Though not confirmed by authorities, it has been reported that the killer in Connecticut tried to buy weapons last week, before using guns his mother owned to kill the children in Newtown.
At present sales made at gun shows are exempt from screening, and it is estimated that 40 per cent of guns are sold at such shows.
Senator Feinstein's proposed legislation would also seek to ban the sale of high-volume magazines which, like the military style semi-automatic rifle, have become a feature of recent mass killings in the US.
On Sunday police confirmed that the killer in Newtown fired hundreds of rounds and shot all his victims more than once in a rampage that lasted only about eight minutes.
There has been little response from gun advocates. The National Rifle Association makes it a practice not to comment after mass killings and on Sunday 31 pro-gun senators declined to appear on an NBC program to debate the issue.
It is not clear if the President will support the Feinstein bill or propose other legislation.
It is also not clear that any gun control legislation would survive a vote in the Senate, where Democrats hold a slim majority, let alone the House, which is controlled by Republicans who tend to walk in lock step with the NRA, America's most powerful lobby.
But it is clear that in speaking so frankly before the people of Newtown, the President has wedded himself to attempt some form of gun law reform, and that as he begins his second term he has less to fear from the NRA.
The President's speech on Monday was worded to keep the memory of Newtown's children central to any debate it causes.
''This is our first task - caring for our children,'' Mr Obama said. ''If we don't get that right, we don't get anything right.
''That's how, as a society, we will be judged. Can we say that we're truly doing enough to give all the children of this country the chance they deserve to live out their lives in happiness and with purpose?
''If we're honest with ourselves, the answer's no.''