Boris Johnson has been speaking alongside Ukraine's President Volodymyr Zelensky in Kyiv after holding talks
He urged Russia to "step back" amid warnings it is planning to invade Ukraine
The prime minister has offered £88m in new UK aid to support Ukraine
US Secretary of State Antony Blinken has told his Russian counterpart, Sergei Lavrov, that "further invasion of Ukraine would be met with severe consequences"
UK Defence Secretary Ben Wallace confirms he will be travelling to Moscow next week for talks
Russia has placed an estimated 100,000 troops, tanks, artillery and missiles near Ukraine's border - but denies it is planning an attack
Western countries are threatening tougher sanctions against Moscow if there is an invasion
Zelensky says the pair discussed deterrents for Russia.
"Any activities are efficient before rather than after. Prevention is better than treatment," he says.
Volodymyr Zelensky begins by welcoming his "friend and partner" Boris Johnson.
He says Johnson's first visit is taking place under "difficult and challenging times" for the world.
He says Johnson assured him of his support for Ukrainian sovereignty.
UK Prime Minister Boris Johnson and President Volodymyr Zelensky have taken to their lecterns and the press conference is starting.
Stay with us for all the updates and analysis. You can watch it live on the BBC News Channel by hitting the 'play' button at the top of the page.
The press conference between Boris Johnson and Volodymyr Zelensky is running a few minutes late, so while we wait, here's the latest from our diplomatic correspondent Caroline Hawley...
There were smiles and there was small talk as TV cameras captured the start of the meeting between Johnson and Zelensky in the elegant Mariisnskyi Palace.
Britain and Ukraine haven’t always seen completely eye to eye on how to respond to the threat posed by Russia.
Kyiv was annoyed last week when the UK followed the US in pulling out some of its diplomats. And President Zelensky had asked the West to tone down its rhetoric about war.
But this meeting is, most of all, a show of solidarity.
As he was setting off for Kyiv, Johnson had tweeted that Ukraine was a “friend and democratic partner".
And he went promising more support – which Ukraine will, undoubtedly, welcome.
Shortly, at a press conference, we’ll learn more about what they actually agreed, as Russia again says that its security demands are being ignored by the West.
President Vladimir Putin says the US has ignored "Russia's fundamental concerns" set down in Moscow's demands for so-called "security guarantees" over Ukraine.
He's been holding a news conference this afternoon following talks with Hungarian Prime Minister Viktor Orban in Moscow.
Putin says he was rereferring to "the three key" demands that Nato does not expand any further, that it does not deploy strike weapons systems near Russia's borders, and that it removes "the bloc's military infrastructure" from states that joined the defensive alliance from 1997 onwards.
Meanwhile, Russia's Foreign Minister Sergei Lavrov has accused the West of trying to forget about the concept of "indivisible security" - a reference to Moscow's claim that any further expansion of Nato would affect Russia’s own security.
During a phone call with US Secretary of State Antony Blinken earlier, Lavrov says he told Blinken "this topic is one we will not let be hushed".
We're expecting a press conference with UK Prime Minister Boris Johnson and President Volodymyr Zelensky to start in around 10 minutes time.
The two leaders have been meeting in Kyiv to discuss the heightened tensions on the border with Russia.
We will bring you all the updates here, so stay with us.
Myroslava Petsa
BBC News Ukrainian, Kyiv
The past few weeks haven’t been easy for the Ukrainians. Television coverage and conversations among friends and family have centred on the threat of an imminent attack by Russia.
Ukrainians describe how they feel fatigued by having to live in a constant state of fear but the events of the recent history have made many much more determined to do whatever they can to defend their country, should it come to that.
Image source, EPAPeople in Kyiv have been joining open civilian military training sessions
James Waterhouse
Kyiv correspondent, BBC News
Image source, PA MediaSo what are the Ukrainians looking for from Britain in the middle of this crisis?
Well, I think more on top of what the UK has already given, such as military training and more lethal weapons.
The UK is held in very high regard in Ukraine, especially this week, and I think President Zelensky is keen to put on the charm offensive.
But it looks like Boris Johnson may be looking to do the same. For example, he arrived wearing a green tie - the president's surname is a play on that colour and it is the colour of his party - so there is some mutual respect there.
The meeting between the pair is going to last for around an hour. In it we expect them to discuss the promise to continue talks, as well as new sanctions on President Putin and Russia as a whole, and the £88m package promised by the UK government to help Ukrainian ministers deal with corruption and become less reliant on Russia for energy.
So, the tone is very friendly here.
Image source, Getty ImagesBoris Johnson travelled to Ukraine this morning
Ahead of the prime minister’s visit, the UK government said it would give Ukraine £88m as part of an attempt to promote stable governance and reduce the country's reliance on Russian energy.
Alongside the announcement, Boris Johnson said: "It is the right of every Ukrainian to determine how they are governed. As a friend and a democratic partner, the UK will continue to uphold Ukraine's sovereignty in the face of those who seek to destroy it."
Foreign Secretary Liz Truss won’t be with the prime minister today after she revealed last night she had tested positive for Covid.
Find out more about why is the UK getting involved in this potential conflict here.
Jonathan Beale
BBC defence correspondent in Zagreb
UK Defence Secretary Ben Wallace has also been been travelling to Eastern and Central Europe, trying to rally support among Nato allies to send a strong message to Russia.
Speaking in Croatia, Wallace said they were “absolutely united” in addressing Russia’s build up of military forces on the border of Ukraine, which he said were a “very grave cause for concern”.
Croatia’s defence minister said “dialogue and diplomacy are the best weapons for de-escalating tensions”.
But while there may be shared concerns about Russia’s intentions, this round of diplomacy has revealed differences too.
Last week the country’s president said in the event of a Russian attack “Croatia should get away from it like a fire” and that Ukraine had no place in Nato.
His comments were slapped down by Croatia’s prime minister. But it illustrates some of the strains within Nato members who are wary of burning bridges with Russia.
Image source, EPACroatian Defence Minister Mario Banozic (right) and the British Defence Minister Ben Wallace both said they hoped the situation could be resolved through dialogue
Jonathan Beale
BBC defence correspondent
UK Defence Secretary Ben Wallace has confirmed to the BBC that he will be travelling to Moscow next week for talks with his Russian counterpart Sergei Shoigu.
Wallace is expected to arrive in Russia on 11 February.
Image source, ReutersMore pictures are coming through of the meeting between Boris Johnson and Volodymyr Zelensky.
The pair are pictured walking through the palace discussing the building's history, with the UK prime minister remarking how much bigger it is than Downing Street.
Johnson and Zelensky are then seen sitting opposite one another at a table, with the prime minister insisting their two countries should "develop our economic partnership".
But, of course, there are more serious discussions to come...
US Secretary of State Antony Blinken has urged an "immediate Russian de-escalation" during a call with Russian Foreign Minister Sergei Lavrov today.
Blinken "emphasised that further invasion of Ukraine would be met with swift and severe consequences and urged Russia to pursue a diplomatic path", Ned Price, spokesman for the US State Department said.
Blinken further reiterated the US commitment to Ukraine’s sovereignty and territorial integrity, he added.
Image source, ReutersUK Prime Minister Boris Johnson has now arrived at the Mariinskyi Palace in Kyiv and is being greeted by President Volodymyr Zelensky ahead of talks over the growing tensions with Russia.
Myroslava Petsa
BBC News Ukrainian, Kyiv
Ukraine certainly feels supported by the West and doesn’t take all the assistance it gets for granted.
The UK has been viewed as one of the strongest allies, after the British government sent the HMS Defender to the Crimean shores and provided anti-tank missiles to Kyiv when Germany rejected the supply of weapons.
Many in Ukraine, including the government, have been frustrated by expressions of “deep concern” of the situation. They want something concrete.
And a vision of a possible tripartite UK-Poland-Ukraine alliance is exactly what Kyiv would want as a show of strength to the growing numbers of Russian troops on its borders.
Boris Johnson’s popularity may not be at its peak in the UK at the moment, but he is a welcome face in Ukraine.
Image source, ReutersPrime Minister Boris Johnson is preparing to hold talks with Ukraine's President Volodymyr Zelenskiy this afternoon.
Ahead of landing at Boryspil airport near Kyiv, Johnson tweeted his support for the country which is facing heightened tensions with Russia.
Quote MessageAs a friend and a democratic partner, the UK will continue to uphold Ukraine's sovereignty in the face of those who seek to destroy it.
Caroline Hawley
BBC diplomatic correspondent
This is a very public show of support to the country caught in the crosshairs between Russia and the West.
Taking a break from his fight for political survival at home, Boris Johnson is keen to show international statesmanship, banking on a warm welcome in chilly Kyiv.
The British government says it’s trained more than 20,000 Ukrainian soldiers and is one of the leading donors of “lethal aid".
Boris Johnson has gone with promises of more support, as the West tries to resolve the crisis by ratcheting up the pressure on Russia.
This involves deterrence - military and economic - and diplomacy.
The prime minister’s spokesman said Johnson was “spearheading the international response".
He’s now due to speak to President Putin tomorrow after the publication of a report on lockdown parties at Downing Street forced a postponement of his call yesterday.
But it’s what Washington says, not London, that really matters to the Kremlin.
Nato - the North Atlantic Treaty Organisation - is the world's most powerful regional defence alliance and its members see an attack on any of them as an attack on all of them.
It was formed in 1949 to counter the threat of post-war communist expansion as the Soviet Union sought to extend its influence in Europe after World War Two.
It originally consisted of 12 founding members - including the UK - and it now has 30, including Lithuania, Latvia and Estonia - former Soviet republics which border Russia.
Ukraine is not a Nato member, but it is a "partner country" - this means there is an understanding that it may be allowed to join the alliance sometime in the future.
Russia wants assurances from Western powers that this will never happen.
But the US is refusing to bar Ukraine from Nato, saying that as a sovereign nation it should be free to decide on its own security alliances.
The Chief of the Defence Staff, Tony Radakin, has been updating ministers on the situation in Ukraine, ahead of the prime minister’s visit.
According to Downing Street, he told a Cabinet meeting earlier that "a significant proportion of Russia's land combat power was now gathered on the western border, coupled with deterrence operations such as military exercises on a scale never seen before".
He told ministers the action fitted into “a pattern of coercion and intimidation that sought to undermine the values and principles of the West".
Boris Johnson has described the situation as "deeply concerning” and says the UK is "leading work" to finalise a package of sanctions which could be applied if Russia did launch an invasion.
Boris Johnson's flight has just touched down at snow-covered Boryspil airport near Kyiv.
The prime minister will meet President Volodymyr Zelensky and a few other officials later for discussions.
We understand Johnson will get a briefing on the situation in Donbas, in the east of the country, where a frozen conflict has been going on between government forces and pro-Russian separatists since 2014.
We’re expecting the two men to hold a news conference later, at around 17:15 GMT, before the prime minister heads back to the UK.
