US President Joe Biden is heading to Europe ahead of a Nato summit after several allies questioned his decision to send cluster bombs to Ukraine.
The UK and Canada are among those who voiced concern about supplying the bombs, which are widely banned because of the danger they pose to civilians.
The US says they are needed because Ukraine’s weapon stocks are dwindling.
Mr Biden will arrive first in the UK, on Sunday evening, before heading to Lithuania for this week’s Nato summit.
On Monday, he will meet British Prime Minister Rishi Sunak to discuss various issues, including the war in Ukraine. He will also meet King Charles for the first time since the King was crowned.
Members of Nato – a military alliance of 31 Western nations – will then meet in Vilnius on Tuesday and Wednesday.
Finland will attend its first summit since joining in April. Plans from Sweden to follow suit have been blocked by Turkey, which accuses it of harbouring terrorists.
Mr Biden is expected to seek further support from Mr Sunak to help broker a deal with Turkey.
The matter is also expected to be on Nato’s agenda in Lithuania – along with boosting ammunition stockpiles and reviewing defence plans.
Ukraine harbours its own ambitions of joining Nato. But speaking to CNN before his trip, Mr Biden said this could not happen until the war was over – in line with the alliance’s long-standing policy.
Citing Nato’s mutual defence pact, Mr Biden pointed out that members undertake to protect “every inch” of each other’s territory – meaning that “if the war is going on, then we’re all in war”.
Ukrainian President Volodymyr Zelensky has previously accepted this position, while requesting a “signal” that his country will be able to join the alliance when the war is over. He is expected to attend this week’s summit.
This is, potentially, an awkward visit coming at a critical time for the US-led Nato alliance.
President Biden may not have intended to cause offence by skipping King Charles’ coronation in May, but his absence was noted.
Then there is the business over who should be the next secretary general of Nato. The UK and the Baltic states favoured the British Defence Secretary, Ben Wallace, who has been instrumental in galvanising Western support for Ukraine.
But without US backing, that’s a non-starter – and Mr Biden instead appears to favour the former German defence minister and European Commission head, Ursula von der Leyen.
And there is also the row over cluster bombs. The UK is among 123 nations to ban these weapons which can cause indiscriminate harm to civilians.
But the US is going ahead, in the heat of international criticism, in supplying them to Ukraine as its forces struggle to break through Russia’s defences in the south of Ukraine.
But Mr Biden’s stopover in Britain is so brief that any cracks in the transatlantic alliance are likely to be smoothed over by warm handshakes and ample protocol.
On Friday, the US confirmed it was complying with a Ukrainian request to send cluster bombs – and was doing so as part of a military aid package worth $800m (£626m).
Mr Biden told CNN it had been a “very difficult decision” but that he had eventually acted because “the Ukrainians are running out of ammunition”.
But a number of Nato allies quickly distanced themselves from the decision.
Mr Sunak did not directly criticise his US counterpart. But he made clear that the UK was one of 123 countries that had signed up to the Convention on Cluster Munitions – an international treaty which bans the production or use of the weapons.
Canada and Spain – Nato members, like the US and UK – also stated their opposition to the weapons, as did New Zealand, a Nato partner.
“No to cluster bombs and yes to the legitimate defence of Ukraine, which we understand should not be carried out with cluster bombs,” Spain’s Defence Minister Margarita Robles said.
But Germany, another signatory of the treaty and Nato member, said that while it would not provide such weapons to Ukraine, it understood the American position.
Cluster bombs typically release lots of smaller bomblets that can kill indiscriminately over a wide area.
One of the concerns surrounding their supply is their failure – or dud – rate. Unexploded bomblets can linger on the ground for years and then indiscriminately detonate.
Ukraine has promised the weapons will not be used in civilian areas and will monitor and report on their use, but Russia dismissed these assurances as “not worth anything”.
