The numbers made this school shooting the most horrific in America's long and painful history of such tragedies – but not just the numbers. The young age of so many of the victims, the self-sacrificial efforts of their teachers, the proximity of Christmas and the picture-postcard New England setting all combined to propel the massacre at Sandy Hook Elementary School in Newtown to the top of the dismal US roll call of gun carnage. But the response was as divided as ever.

From Europe came the standard explanation that it was all about the availability of guns and the endemic violence of US society – condemnation that found an echo with those many Americans who favour stricter gun control. Then from the powerful US gun lobby came the defence that it is not guns that kill people, but people that kill people. Thus simplistically – too simplistically – are the battle lines drawn up.

It is not as though either Europe in general, or Britain in particular, has not had its own gun massacres, despite very strict firearms laws. Mass shootings in Britain did not end with the slaughter of 16 children at Dunblane, though the law was subsequently tightened further. What price, too, the apparent social calm of Scandinavia, when one fanatic could kill 77 people at a Norwegian youth camp? Connecticut, after all, has some of the strictest gun controls in the US. Laws cannot prevent everything.

They can, though, do a lot. There is no comparison between the number of gun deaths each year in Britain and the US, either in absolute terms or in proportion to the size of the population. The atrocity at Newtown was the third multiple shooting in the US this year. And, unusually, the US has a President who was elected and re-elected despite his unapologetic advocacy of gun control. That he is starting a second term and cannot seek another gives him more freedom of manoeuvre on this divisive topic than he would have had four years ago.

He seemed also to take the Newtown shooting very personally, showing a rawness of emotion unusual for him. And he suggested a readiness to use his authority to curb US gun excesses. "We have been through this too many times," he said. "We're going to have to … take meaningful action to prevent more tragedies like this, regardless of the politics."

That, though, will be easier said than done. For a start, "the politics" cannot be so summarily dismissed. Gun control is an even more sensitive issue in the US than healthcare, and we saw how difficult it was for Mr Obama to enact even a modest extension of health insurance. Nor has he shown himself especially adept at reaching out to his Republican opponents.

Even in the unlikely event that support did emerge in Congress for a radical change in the US attitude to guns, it would take an amendment to the Constitution, which guarantees all Americans the right to bear arms. This in turn would require a two-thirds majority in both Houses, plus a vote in favour by 38 state legislatures – which would be nigh-impossible, with so many Southern and Midwestern states against – or a constitutional convention, which would be without precedent.

With passions running so high, however, and a strong impetus from the President, some reform might be possible. The Governor of Connecticut called yesterday for assault weapons to be outlawed federally, noting that it was hard for one state to enforce a ban that did not exist nationally. Less variation in state laws might not have prevented these deaths, but if it helped to thwart the malign intent of another disturbed individual in future, it would be a worthier legacy for Newtown than no action at all.