Image source, Reuters

Germany and Poland share a 467 km border (290 miles), and both are Nato members.

And earlier, German Chancellor Olaf Scholz spoke to Polish President Andrzej Duda and expressed his condolences over the incident along its border with Ukraine, a government spokesman says.

In a tweet, external, spokesman Steffen Hebestreit says Germany stands close to Poland, "our Nato partner".

As we've been reporting, there's been "no indication" that the missile strike which killed two in Poland was a deliberate attack by Russia, or that Russia is preparing military action against Nato, according to Nato Secretary General Jens Stoltenberg.

The blast was most likely caused by Ukrainian air defence, the Polish President Andrzej Duda has said.

Nato - the North Atlantic Treaty Organization - is a defensive military alliance with 30 member states across Europe and North America.

This includes three of the five permanent members of the UN Security Council - the UK, US and France. Members agree to help one another if they come under armed attack.

The bloc expanded after the breakdown of the Soviet Union, and now includes several Russian neighbours in Eastern Europe – including Poland.

Since Russia's invasion in February, Ukraine, Finland and Sweden have all applied to join.

Read more about Nato here

Image source, Reuters

Thanks for joining our live coverage. Here's a quick look back over another busy morning.

• More suggestions have been made that the explosion of a missile in a Polish village was caused not by a Russian attack - but by the activities of Ukraine's air defence systems
• It was feared that the explosion could spell a major escalation in the war between Russia and Ukraine. Two civilians were killed in the Polish blast; an investigation is ongoing
• The head of Nato - a military alliance of Western countries which opposes Russia's invasion of Ukraine - said there was "no indication" of any deliberate Russian attack, adding that the blast was "likely" caused by Ukrainian defences. His view echoes that of the Polish president
• Ukrainian President Volodymyr Zelensky was quick to blame Russia for the explosion in Poland - something denied by Moscow. The Kremlin issued rare praise for the United States after President Joe Biden said it was "unlikely" the missile was Russian
• Ukraine's position now appears to have softened - with one official calling for a "joint study" into the incident, and access to the site of the explosion
• In Ukraine itself, people have been warned to prepare for prolonged energy restrictions, after Tuesday's bombardment by Russia - the most intense since the war began - damaged key infrastructure and triggered power cuts

Paul Adams
BBC Diplomatic correspondent

Image source, AFP

This was the moment Western leaders have feared since Russia launched its all-out invasion in February: that the war might spill over onto the territory of one of Ukraine’s Nato neighbours, forcing Nato to respond and thus widening the conflict.

But early fears that Russia might have deliberately attacked Poland quickly faded, as analysts and then Western politicians lined up to say this did not look like a deliberate Russian attack.

After this morning's Nato meeting, the alliance's Secretary General, Jens Stoltenberg, said that his preliminary analysis showed that the wreckage filmed at the site was part of a Ukrainian air defence missile.

But, he added, this was not Ukraine's fault. After all, none of this would have happened if Russia hadn’t launched dozens of cruise missiles yesterday at targets all across Ukraine.

Not Ukraine's fault, but questions will be raised about Kyiv’s early denial that one of its air defence missiles was involved.

Ukraine’s Foreign Minister, Dmytro Kuleba, last night tweeted that any suggestion a Ukrainian missile had landed in Poland was a Russian "conspiracy theory".

In light of subsequent comments from Joe Biden, his Polish counterpart, Duda, Stoltenberg, the Danish defence minister and others, Kuleba's tweet seems hasty.

Hot on the heels of those remarks from the Nato chief, we've had further comment from the Ukrainian side on that missile explosion in Poland which killed two people late on Tuesday.

An official calls for a "joint study" on the "incident". Oleksiy Danilov adds that Kyiv expects its allies to provide evidence for their suggestions that the deadly blast may have been caused by Ukraine's air defences.

The head of the National Security and Defence Council adds in his tweet, external that Ukraine is requesting "immediate access to the site of the explosion".

Danilov's words appear to represent a softening of Kyiv's position. President Volodymyr Zelensky initially blamed Russia for the blast in Poland - something Russia was quick to deny.

Image source, Getty Images

Nato Secretary General Jens Stoltenberg has been giving a press conference after a missile strike killed two people in Poland. Here's a recap of what he said.

• There is "no indication" of a deliberate attack by Russia, or that Russia is preparing military action against Nato
• The blast was most likely caused by Ukrainian air defence, but investigations are ongoing
• However, Nato does not consider this Ukraine's fault as it has the right to defend itself
• Instead, Russia bears the "ultimate responsibility" for the attack in Poland, because of its invasion of Ukraine
• Poland has not requested a meeting with other Nato countries under the terms of Article 4 of the treaty, which countries can use if they think their security is threatened
• Stoltenberg's tone throughout the conference was one of calm and de-escalation, and he re-iterated calls for Russia to end its invasion

The final question to the Nato chief is about Nato's response to the incident in Poland. Stoltenberg says Nato allies reacted in a "well-coordinated way".

He says the exchange of information between allies was effective, allowing for a coordinated and measures response.

He adds that the response was about being "calm" and preventing any "unnecessary escalation".

"I believe that China should clearly condemn the invasion of Ukraine," says Stoltenberg in reply to another reporter's question. China has tried to walk a tightrope by declining to explicitly denounce Moscow's actions.

He then turns to the topic of peace. "Most likely this war will at some stage end at the negotiating table," he opines. Stoltenberg says this matter is "closely linked" to Ukraine's performance on the battlefield as it continues to defend its status as an independent nation.

Nato's support for Kyiv will "maximise the likelihood for a peacefully negotiated solution," Stoltenberg says.

Next, Stoltenberg is asked whether the explosion in Poland represented a failure of Nato defences.

He gives a robust response, saying the missile hit didn't have the "characteristics" of an attack, which "explains why the actions were what they were".

He reiterates that preliminary evidence is suggesting the blast was caused by a Ukrainian air defence missile.

Asked about Ukrainian claims yesterday that the missile explosion in Poland was a "Russian conspiracy theory," and how different Nato's preliminary findings are, Stoltenberg again says the investigation is not finally concluded, but based on what they know so far, it was "most likely" a Ukrainian air defence missile.

He goes to Ukraine's defence, however, stating that the incident was "not Ukraine's fault".

"Russia bears responsibility for what happened in Poland yesterday," he says, because it was a "direct result" of the ongoing war and wave of attacks on Ukraine by Russia.

Asked what his reaction to the missile explosion was, he says though he was saddened by reports that there were two casualties, Nato is constantly preparing to handle such situations in a "calm" and "resolute" manner.

Continuing to answer reporters' questions, Jens Stoltenberg says Nato's "top priority" is to provide Ukraine with more air defence systems against Russian attacks.

He re-states that Ukraine has a right to self-defence in the wake of February's invasion by Moscow - but reiterates that Nato itself is not a "party" in the war between the neighbours.

Stoltenberg is again careful to point out that a missile which landed in Poland late on Tuesday - killing two civilians - does not appear to have been fired by Russia, according to the findings of an investigation so far.

More from Jens Stoltenberg, who says he "cannot go into details" about conversations with Russia following the blast in Poland.

He was responding to a question about Nato's communications with Moscow following the explosion late on Tuesday.

Asked whether he can give more details regarding the missile explosion in Poland, Stoltenberg says it would not be right to give more details while an investigation is ongoing, reiterating that preliminary findings show it was likely a Ukrainian air defence missile.

Replying to another question, Stoltenberg describes the "significantly increased" Nato presence in Eastern Europe - which he says covers land, sea and air.

He says the military alliance's defences against air attacks will continue to be strengthened as a result of the "incident" in Poland.

Stoltenberg says he welcomes more and more allies providing air defence systems to Ukraine.

"We are mobilising additional support," he says, especially different types of air defences.

Stoltenberg is asked by the BBC's Jessica Parker whether this is the most tense moment of the war so far for Nato.

In his response, he says he is "careful" about ranking risky moments, and alludes to ongoing "dangerous situations" caused by the conflict.

He calls attention to a "wave" of Russian strikes on Ukraine on Tuesday, which killed civilians and damaged critical infrastructure.

Stoltenberg says Nato allies have expressed their "strong support" for their ally Poland and expressed their "deepest condolences for the tragic loss of life" following the missile explosion.

He adds that it has significantly increased its military presence in the east since Russia's invasion of Ukraine.

"We are constantly assessing what more we need to do," he says.

Image source, Reuters

Stoltenberg continues by saying the incident in Poland was "likely" caused by the activity of Ukraine's air defence systems - echoing the view of the Polish president.

But the Nato chief is clear that "Russia bears ultimate responsibility as it continues its illegal war against Ukraine".

Nato chief Jens Stoltenberg says there is "no indication" the missile explosion in Poland was the result of "a deliberate attack".

"There is no indication that Russia is preparing offensive military actions against Nato," he says.

He adds that the investigation is ongoing and the outcome must be awaited.

We're now hearing from Jens Stoltenberg, the leader of the Nato military alliance of Western countries.

He's giving a press conference as the alliance responds to a deadly explosion in a village in Poland near the Ukrainian border - the exact cause of which remains unconfirmed.

We'll let you know what he says.