New Zealand just announced sweeping new gun laws that may cost the country up to $138 million. Here's how they'll work.

New Zealand Prime Minister Jacinda Ardern announced a ban on all “military-style semiautomatic weapons” and assault rifles days after the country's worst mass shooting, in Christchurch.The ban went into effect at 3 p.m. local time and is set to be law by April 11.The government said it would also introduce a gun-buyback program, offering cash incentives to those who still have the weapons.The program is estimated to cost $69 million to $138 million. An amnesty period will allow people to hand in their banned weapons within a reasonable amount of time.New Zealand Prime Minister Jacinda Ardern announced a ban on all “military-style semiautomatic weapons” and assault rifles on Thursday, six days after the country's worst mass shooting.“Today I am announcing that New Zealand will ban all military-style semiautomatic weapons,” Ardern said at a press conference. “We will also ban all assault rifles,” she continued. “We will ban all high-capacity magazines. We will ban all parts with the ability to convert semiautomatic or any other type of firearm into a military-style semiautomatic weapon. We will ban parts that cause a firearm to generate semiautomatic, automatic, or close to automatic gunfire.” Ardern said that the ban on selling or possessing those weapons went into effect at 3 p.m. local time on Thursday and that it's an “interim measure” while legislation is prepared. She said she hoped the ban would be law by April 11.“This is just the beginning of the work we need to do,” Ardern said, adding that the existing laws do not “go far enough.”What does the ban mean？Tweet Embed: //twitter.com/mims/statuses/1107483050705772544？ref_src=twsrc%5Etfw Until today I was one of the New Zealanders who owned a semi-automatic rifle. On the farm they are a useful tool in some circumstances, but my convenience doesn‘t outweigh the risk of misuse.We don’t need these in our country. We have make sure it‘s #NeverAgain pic.twitter.com/crLCQrOuLcThe country has made immediate changes to licensing regulations, designed to make it more difficult for buyers to get their hands on assault weapons.Previously, a legal loophole allowed many people to purchase military-style semiautomatic weapons, or MSSAs, without a specially designated license — because MSSAs are defined by law by their parts, modifying them could let people purchase them without the need for that license.Two types of firearms have now been reclassified as MSSAs:Semiautomatic firearms capable of being used with a detachable magazine that can hold more than five cartridges.Semiautomatic shotguns capable of being used with a detachable magazine that can hold more than five cartridges.As of Thursday at 3 p.m. local time, those without a certain license cannot legally possess MSSAs.Read more: What we know about the guns used in the Christchurch attacks, and how New Zealand's gun laws could change after the massacreThe government says there are 245,000 firearms licenses in New Zealand and an estimated 1.2 million to 1.5 million firearms.Ardern discussed a national buyback plan to offer “fair and reasonable” compensation to gun owners wishing to hand in their guns voluntarily.She said the program could cost $69 million to $138 million, adding that there would be an amnesty period to allow people to hand in their banned weapons within a reasonable amount of time.The program would allow people to go online and fill out a form with the police to arrange the safe return of their weapons. They can also sell or gift their weapons to those who are in possession of a “Category-E” license necessary to own MSSAs. Once the full ban comes into effect, the penalties for those who don't hand in their guns will increase, Ardern said. Owning an assault weapon without the correct category license is punishable by up to three years in prison or a fine of about $2,750.Ardern said her cabinet will also consider further legislation to tighten firearm licensing and better control ammunition types.Ardern says there is already support for the banOn Thursday, the prime minister said that many have already expressed support for tightening gun legislation. “I absolutely believe there will be a common view amongst New Zealanders, those who use guns for legitimate purposes, and those who have never touched one, that the time for the mass and easy availability of these weapons must end,” she said. “And today they will.”It took New Zealand less than a week to make changes to its gun laws following the mass shooting at two mosques in Christchurch that left 50 dead, and the move received broad positive feedback from around the world. She added that the government sought advice from countries like neighboring Australia, which overhauled its gun laws in 1996 just 12 days after it experienced its deadliest mass shooting in the town of Port Arthur, Tasmania. New Zealand's Police Association said it supported the government's decision for “demonstrating the courage to take decisive action and ban the firearms that have inflicted so much harm in New Zealand.”Lobby group Federated Farmers issued a statement in support of tighter gun laws, but admitted the decision would not be popular amongst some of its members.New Zealand's opposition leader Simon Bridges of the New Zealand National Party released a statement in support of Ardern's decision. National has been clear since this devastating attack that we support changes to our regime and that we will work constructively with the Government, he said. This contrasts with how US politicians respond following mass shootings, which Rep. Alexandria Ocasio-Cortez pointed out on Twitter. She called out US leadership for failing to pass stricter gun legislation despite an uptick of major mass shootings in recent years. Tweet Embed: //twitter.com/mims/statuses/1108563593304436736？ref_src=twsrc%5Etfw Sandy Hook happened 6 years ago and we can’t even get the Senate to hold a vote on universal background checks w/ #HR8.Christchurch happened, and within days New Zealand acted to get weapons of war out of the consumer market.This is what leadership looks like ⬇️ https://t.co/TcdR63anBtAround 11,000 people in the US are killed annually in firearm assaults, and Americans are more likely to die from gun violence than many leading causes of death combined.