President Barack Obama announces a host of measures to crack down on gun violence following the deaths of 20 children at a primary school in Connecticut.

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President Obama has decided to act quickly to ban military-style assault weapons and high-capacity ammunition clips after last month's shootings in Newtown.

He wants background checks on people who buy guns to be stepped up, along with a new law against gun trafficking to stop gangs from buying weapons in states with lax gun laws and transporting them to states with stricter laws.

None of these measures is likely to be popular with Republicans in the House of Representatives, and there are also Democrats in the Senate who are opposed.

But the president said: "This is our first task as a society - keeping our children safe" adding that it was time to take action against an "irresponsible law-breaking few", despite the inevitable complaints from the gun lobby about a "tyrannical, all-out assault on liberty".

Twenty six and seven-year-olds were shot dead at their primary school when Adam Lanza opened fire with a semi-automatic weapon, frequently changing his gun clips so he could unleash 150 rounds in 10 minutes. Six members of staff were also killed.

The president has signed 23 executive orders aimed at circumventing congressional opposition to stricter gun control.

These orders mean President Obama will be able to force through some of the changes without congressional approval, such as making background checks easier.

But congressional approval is needed for his plans to outlaw assault weapons and 10-round ammunition clips.

The president made his announcement at the White House alongside four children who wrote to him after the killings. Some of the families of victims of the shootings were also present.

Gun lobby

He is taking on America's powerful gun lobby, which is opposed to strict controls on weapons.

The US has the highest rate of gun ownership of any country in the world, and pro-gun groups see any move on restrictions as an offence against the second amendment of the constitution.

Read more: Gun control - what can America learn from Britain?

President Obama has described the day of the shootings - 14 December - as the worst of his presidency. Gun control advocates worry that opposition from the powerful National Rifle Association (NRA) and its allies in congress will be too great to overcome.

The NRA released an online video on Tuesday (see above) calling Mr Obama an "elitist hypocrite" because while his daughters are protected by armed secret service agents at school, he is not committed to installing armed guards in all schools, a policy it supports.

Before the announcement, White House officials said there was not a single measure, such as banning assault weapons, that would solve gun violence.

Taskforce

President Obama's proposals are based on recommendations from Vice President Joe Biden, who led a taskforce on gun violence.

Beyond the gun control measures, Mr Biden also gave the president suggestions for improving mental healthcare and addressing violent images in video games, films and television.

Action is already being taken by some US states. New York has just signed into law some of the toughest gun controls in the US, with restrictions on assault weapons and measures to ensure that guns do not fall into the hands of the mentally ill.

Action

New York is the first state to act since the Newtown shootings.

President Obama has his work cut out as he tries to convince congress to back his proposals.

Mitch McConnell, the Senate's top Republican, has warned him that it will be at least three months before gun legislation is considered. Senate majority leader Harry Reid, a Democrat, has said immigration, not gun control, is his priority.