LONDON — The United Kingdom and the European Union have signed a new agreement intended to solve one of the thorniest challenges created by Brexit: a long-term resolution for the trading status of Northern Ireland.

British Prime Minister Rishi Sunak reached a deal with European Commission President Ursula von der Leyen on Monday that will allow goods to enter Northern Ireland freely from other parts of the U.K.

It comes more than six years after British voters chose to leave the EU and three years since the two finally broke up in 2020.

One reason the Brexit process dragged on for so many years was the inability of all sides to address a double dilemma: How to avoid a hard border on the island of Ireland that might become a flashpoint given the region's troubled history, and how to ensure Northern Ireland was not somehow treated separately from the rest of the United Kingdom.

Here's how the deal, dubbed the "Windsor Framework" — a change to the original Northern Ireland Protocol — attempts to solve those issues.

It revises trade rules

Then-Prime Minister Boris Johnson's government opted to let the EU grant Northern Ireland a rather unique status, meaning that goods produced elsewhere in the U.K. — England, Wales or Scotland — would need to be inspected by officials before they could enter Northern Ireland.

Leaders were trying to avoid creating a hard border between Northern Ireland, which was leaving the EU, and neighboring EU-member state Ireland. But their solution also created a fresh set of challenges.

People in Northern Ireland who strongly want to remain part of the U.K. saw this as an affront. One of the main political parties there, the Democratic Unionist Party (DUP), has consequently refused to participate in local government ever since. It has helped reignite some tensions between different communities.

At the same time, some members of the Conservative Party also resented the idea that even after Brexit — with its slogan to "take back control" of Britain — EU bureaucrats would continue to have the power to intervene in trade flows within the United Kingdom.

The new plan involves the introduction of red and green lanes for goods arriving in Northern Ireland from other parts of the U.K.: green for British products, including medication, that are staying in Northern Ireland; red for those goods and products that will be sold on to the Republic of Ireland, thus entering the EU.

Business groups welcomed Monday's changes.

It might break the deadlock in Northern Ireland's politics

Sunak has called this a "decisive breakthrough" and says that the U.K. Parliament will get a vote on the plan at the "appropriate" moment. But several lawmakers who opposed the previous agreement said they want some time to digest the new details before passing judgment.

In a parliamentary debate that followed the deal's announcement, one of Sunak's predecessors, Theresa May, who struggled to solve the Northern Ireland dilemma and ultimately failed to win lawmakers' approval for a Brexit deal, said the newly agreed measures will "make a huge difference."

Meanwhile, Sunak's chief political opponent, Labour Party leader Keir Starmer, said he would support the new deal, which would boost Britain's international standing and hopefully put an end to the country's "endless disputes" with its neighbors.

Sunak has also promised that the local legislature in Northern Ireland, known as the Stormont Assembly, will have the ability to diverge from European Union laws, in a way that was difficult under the previous deal.

The DUP has, over the past two years, refused to take part in the power sharing agreement in Northern Ireland, essentially grinding local governance to a halt, and thus potentiality endangering the 1998 Northern Ireland peace agreement.

Sunak will be hoping this breaks the gridlock and calms some of the tensions that the entire Brexit process has reawakened in the region — only last week gunmen tried to kill a senior police officer in Northern Ireland.