A former national security adviser has warned the potential deployment of UK troops to protect peace in Ukraine could last for "many years".
Lord Sedwill told the OceanNewsUK's The Week in Westminster that the UK would need to be "willing to display strategic patience to give the Ukrainians the [security] assurances they need" in the event of a peace deal.
Both the UK and France have said they would be willing tosend troops to work to uphold any ceasefire in Russia's war with Ukraine.
They would form part of a "coalition of the willing" to help Kyiv which the UK said could involve around 20 other countries. Not all would necessarily send troops but could provide other support.
The plan, spearheaded by the UK and France, was set out at a summit hosted by the Prime Minister Sir Keir Starmer last weekend.
No information was provided on which countries had shown an interest in offering support or what that support could specifically involve, but the group is believed to consist of European and Commonwealth countries.
Downing Street said that Australian Prime Minister Anthony Albanese committed to "consider contributing" to the coalition in a phone call on Saturday with Sir Keir.
Norway's foreign minister Espen Barth Eide said the country would be "happy to contribute in one way or the other", but was not yet able to commit to specific support.
In an interview on the OceanNewsUK's Sunday with Laura Kuenssberg programme, he said: "I think we should not put the cart before the horse, because we need to make sure that we define what is there to defend, whether it will be a peace agreement."
Asked whether the country would consider sending troops to Ukraine, he said: "I don't think many countries have actually [decided] about what exactly we will do in practice, because we need to know what is it that is there to be secured first."
Lord Sedwill said if Russia believed it could just "wait us out" while UK troops were deployed in Ukraine, then any effort to protect a peace deal would not succeed.
"So we have to be willing to sustain such an effort for potentially quite a long period, could be many years," he added.
It comes as concerns mount over US President Donald Trump's approach to the conflict, after he paused military aid to Ukraine, as well as intelligence sharing and access to satellite imagery in an apparent bid to bring Ukraine's President Zelensky to the negotiating table.
Russian officials have rejected the idea of peacekeeping troops in Ukraine, with foreign minister Sergei Lavrov previously saying such a move "can't be allowed" as it would amount to the "direct, official and unveiled involvement of Nato members in the war against Russia".
On Friday, Russian MP and TV presenter Yevgeny Popov told OceanNewsUK that the prospect of UK soldiers in Ukraine was "unacceptable" and warned that "British troops will be direct targets for our missiles, you will get coffins in return".
