Home Secretary James Cleverly has signed a new treaty with Rwanda designed to address concerns about the government's plan to send asylum seekers there.
In November, the UK Supreme Court ruled that the scheme was unlawful because of the risk that asylum seekers sent to Rwanda could be returned to their home countries, where they could face harm.
What is the UK's new asylum treaty with Rwanda?
The government says this guarantees that any people sent to Rwanda to claim asylum are not at risk of being sent to a third country where they could face harm.
It also announced a new independent monitoring committee to ensure Rwanda complies with the treaty, and a new appeal body.
Reports have suggested that British lawyers may also be sent to the country to help strengthen its asylum system.
What did the Supreme Court say about the Rwanda policy?
The UK Supreme Court ruled unanimously that the Rwanda scheme was unlawful.
Five leading judges said the Court of Appeal had been right to conclude in June that there had not been a proper assessment of whether Rwanda was a safe country for asylum seekers.
Court president Lord Reed said there was strong evidence to believe that genuine refugees sent to the country could be returned to their home countries where they could face persecution. In law, this is called "refoulment".
This breaches part of the European Convention on Human Rights (ECHR), which prohibits torture and inhuman treatment. The UK is a signatory to the ECHR.
The judges also said the policy breaches safeguards in three British laws passed by Parliament during the last 30 years.
They cited concerns about Rwanda's poor human rights record, and its past treatment of refugees.
The United Nations Refugee Agency (UNHCR) told the Court that the Rwandan government turned down100% of all asylum claims made by people from Afghanistan, Yemen and Syria between 2020 and 2022.
The Rwandan government rejected the judges' conclusions, saying: "We take our humanitarian responsibilities seriously, and will continue to live up to them."
After November's ruling, Prime Minister Rishi Sunak said he remained "completely committed to stopping the boats", and was determined to "end the merry-go-round" of legal challenges.
What else is the government doing to address the Supreme Court concerns?
The government is also preparing emergency legislation to declare that Rwanda is a safe country, but legal experts have questioned how that might work.
Former Supreme Court judge Lord Jonathan Sumption told the BBC that the government's plan to get round the Supreme Court ruling this way was "profoundly discreditable", and that the policy would still be a breach of the government's international law obligations.
"It would be constitutionally a completely extraordinary thing to do, to effectively overrule a decision on the facts, on the evidence, by the highest court in the land," he said.
What is the Rwanda asylum plan?
Under the five-year trial - first announced in April 2022 - some asylum seekers arriving in the UK would be sent to Rwanda for processing.
On arrival, they could be granted refugee status and allowed to stay. If not, they could apply to settle there on other grounds, or seek asylum in another "safe third country".
The government said that "anyone entering the UK illegally" after 1 January 2022 could be sent there, with no limit on numbers.
Rwanda could also ask the UK to take in some of its most vulnerable refugees.
The UK has already paid the Rwandan government £140m, but no asylum seeker has actually been sent there.
The first flight was scheduled to go in June 2022, but was cancelled after legal challenges.
Why does the government want to send asylum seekers to Rwanda?
The government said the policy would deter people arriving in the UK through "illegal, dangerous or unnecessary methods", such as on small boats across the English Channel.
More than 45,700 people used this route to come to the UK in 2022, the highest figure since records began.
In January the PM said "stopping the boats" was one of his key priorities.
As of 4 December, the total number of small boat crossings in 2023 was a third lower than at the same point in 2022. But it is not clear which government policies have contributed to that fall.
Where is Rwanda?
Rwanda is a small land-locked country in east-central Africa, 4,000 miles (6,500km) south-east of the UK.
It borders Burundi, the Democratic Republic of the Congo (DRC), Tanzania and Uganda.
With a landmass about one-tenth of the size of the UK, it has a population of 13.8 million.
President Paul Kagame hopes to win a fourth term in 2024, which would extend his presidency to nearly three decades.
He won the last presidential election in 2017 with nearly 99% of the vote, but critics accuse him of supressing his opponents.
According to Human Rights Watch, "Rwanda is a country where it's very dangerous to oppose the government".
Would the plan save the government money?
The government has not provided a total cost for the scheme.
But speaking to journalists on a flight to Dubai for the COP28 climate summit, the prime minister said that the Rwanda plan will "literally save us billions in the long run".
He did not give details to back up this claim.
An economic-impact assessment prepared for the government's Illegal Migration Bill estimated that removing each individual to a third country, such as Rwanda, would cost £63,000 more than keeping them in the UK.
That is the difference between the total cost of removing an individual - estimated to be £169,000 - and the £106,000 spent on housing support if they remain in the UK.
The latter figure includes a payment to the third country of around £105,000 per person, as well as £22,000 for flights.
The Home Office said no cost would be incurred if the policy prevented an individual from entering the UK illegally.
But it acknowledged it could not say how many people would be deterred.
The UK's asylum system costs £3bn a year. About £8m a day is spent on hotel accommodation for refugees and asylum seekers.
Critics say the daily cost is so high because of the time taken to decide on applications, and a ban on asylum seekers working while waiting for confirmation of their status.