As Russia's invasion of Ukraine continues to devastate the country and claim thousands of lives, many across the world are looking for ways to help - including joining the military fight against Moscow.
Retired and serving British soldiers, and even citizens, have expressed their desire to support the Ukrainian resistance - but there has been confusion over whether they would be allowed to go.
The Foreign, Commonwealth and Development Office (FCDO) continues to advise against all travel to Ukraine and told ITV News that "anyone who travels to conflict zones to engage in unlawful activity should expect to be investigated" when they return to Britain.
However, Foreign Secretary Liz Truss has said she would "absolutely support" British nationals who want to join the fight.
Questions have been raised about the legality of Britons going abroad to fight in previous foreign conflicts and whether the same laws could apply to the Ukraine war.
What is the UK travel advice for Ukraine?
As of February 11, the FCDO has advised Britons against all travel to the whole of Ukraine.
It has also been urging British nationals to evacuate.
The FCDO's official advice says: "The Russian invasion of Ukraine is ongoing, with attacks against a number of major cities. There is a real risk to life.
"We advise British nationals to leave Ukraine immediately if you judge it is safe to do so. Ukraine’s airspace is closed."
Can British citizens travel to Ukraine to fight?
Earlier this week, Ukrainian President Volodymyr Zelenskyy called for foreign volunteers to go to Ukraine and form an "international legion", promising them arms to fight against the Russian troops.
When the foreign secretary was asked if she would support UK citizens who chose to answer the call, Ms Truss told BBC’s Sunday Morning programme: "I do support that and of course, that is something that people can make their own decision about.
"The people of Ukraine are fighting for freedom and democracy, not just for Ukraine but for the whole of Europe, because that is what President Putin is challenging."
"Absolutely, if people want to support that struggle, I would support them in doing that," she added.
However, Downing Street and Defence Secretary Ben Wallace later effectively contradicted Ms Truss' comments.
Mr Wallace urged Britons not to travel to Ukraine to join the fighting as he said the “very dangerous” situation could lead to them being killed.
The defence secretary, who served in the Scots Guard, said it was a "just cause" for Ukrainians to return to fight but reiterated the risks.
He added: “If you're British and you just want to go and do this, and fight, I would give strong advice that if you want to help in that world - join our Armed Forces."
The Ministry of Defence has announced a host of new deployments in recent weeks.
British troops and tanks have been deployed to Estonia, near Russia’s border, while Royal Navy ships are at sea in the Mediterranean and Royal Air Force jets are conducting missions over Poland and Romania, intended to reassure allies.
But Mr Wallace said "you have to be a trained person" and it would be dangerous for amateurs to join the efforts, adding there are "better ways" for Britons to help.
Prime Minister Boris Johnson’s official spokesman said: "The best way we can help Ukraine right now is by ensuring Putin fails.
"There are a number of ways Brits can show their support for that, and the Ukrainian embassy in London is putting out information about how British people can support.
“We fully recognise the strength of feeling about British people wanting to support the Ukrainians following the Russian invasion. There’s advice up on travelling to Ukraine, we currently advise against travel to Ukraine.”
Is it illegal for Brits to join the Ukrainian fight?
When ITV News asked the FCDO if Brits travelling to Ukraine to fight would face prosecution, the spokesperson replied: "We advise against travel to Ukraine and anyone who travels to conflict zones to engage in unlawful activity, should expect to be investigated upon their return to the UK.”
However, they did not clarify what would be considered "unlawful activity".
In 2014, the Crown Prosecution Service warned that UK nationals who went to fight in the Syrian civil war could be committing an offence, even if they joined the rebels fighting to overthrow President Bashar Assad.
Despite Ms Truss' comments, questions have been raised about whether Britons could face similar criminal action if they go to Ukraine.
An FCDO spokesperson told ITV News: “We advise against travel to Ukraine and anyone who travels to conflict zones to engage in unlawful activity, should expect to be investigated upon their return to the UK.”
Former Brexit Secretary David Davis said on LBC: "I think actually it's illegal to go and fight in a foreign war these days".
He pointed to the Foreign Enlistment Act of 1870 which bans Britons from fighting in the "military or naval service of any foreign state" that is at war with a country that the UK is "at peace" with.
"There are certainly laws restricting who you can go and fight for already," he told the radio show.
However, he added: "People fought on various sides of the Spanish Civil war without being penalised when they came back".
Can British soldiers join the fight in Ukraine?
An Army spokesperson told ITV News that "all Service Personnel are prohibited from travelling to Ukraine until further notice".
"This applies whether the Service Person is on leave or not. Personnel travelling to Ukraine will face disciplinary and administrative consequences. The only personnel exempt from this order are those whose official duties require presence in Ukraine such as Defence Attaché staff," added the spokesperson.
It comes after a leaked message on the British Army's internal messaging service saw military chiefs ban soldiers from heading to Ukraine.
The note, shared on February 28, read: "There has been some recent media coverage relating to foreigners being welcomed into Ukraine to help fight against Russia.
"To be clear, as members of the British Army, you are not authorised to travel to Ukraine to support the ongoing conflict against Russia in any form, whether you are on leave or not.
"Please remain professional and focused on your duty and your team."