Boris Johnson has made clear the UK will not send troops to Ukraine if Russia launches a full-scale invasion, but there are other ways of aiding the European ally.

Moscow sent “peacekeeping” forces into Russian-backed rebel-held areas of western Ukraine on Monday night, after President Vladimir Putin said the country would recognise the self-proclaimed republics of Donetsk and Luhansk as two independent states.

Following the move, Prime Minister Boris Johnson said President Putin has “denied Ukraine’s legitimacy as a state” and is “establishing the pretext for a full-scale offensive”.

Mr Johnson announced sanctions on five Russian banks and three oligarchs, but is facing calls to go further.

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Why has the UK said it will not send in troops?

The British government has been clear its response will not involve British combat forces in Ukraine, as it is not part of NATO, but they have been training Ukrainian forces for years.

Training only stopped a few days ago as tensions with Russia increased further.

Despite this, the UK and other allies have increased numbers of troops in NATO countries surrounding Ukraine.

What weapons has the UK already sent to Ukrainian forces?

With Russian forces amassing at the border over recent weeks, the UK responded by sending Ukraine “self-defence” weapons.

These include anti-tank missiles – one is the Javelin anti-tank guided missile that uses infrared guidance to hit tanks from the top and can be used against buildings and helicopters.

The other is the Next Generation Light Anti-tank Weapon (NLAW), developed by the UK and Sweden, which is launched on the shoulder and can be fired from confined spaces.

The UK is also providing intelligence to Ukraine, as are other NATO members.

Both the US and the UK are also helping Ukraine manage Russian cyber attacks, which could lead to many Ukrainian deaths if key infrastructure is taken over by Moscow.

But, they are unlikely to get involved with cyber warfare, which would be considered direct involvement.

A weapons ‘shopping list’

Professor Malcolm Chalmers, deputy director-general of leading defence think tank RUSI (Royal United Services Institute), said Ukraine will likely give NATO “a shopping list” and there would likely be a discussion about who could provide what.

The defence expert, who held meetings in Moscow with Russian officials last week, said one of the extra options the UK could provide are intelligence surveillance reports.

He said the UK will likely fly planes over neighbouring countries, such as Poland, where they can see into Ukraine but will not be directly involved in the conflict.

“Where it gets difficult and begins to move into the grey area between being involved directly or not is when you start talking about special forces or operations within Ukraine – that’s a line I think the government would be pretty reluctant to cross but will be on the agenda,” he said.

Prof Chalmers said he did not think the UK would send over large equipment as Russia’s superior force would destroy it quickly and Ukrainian forces would need training on how to use and maintain it.

But he said drones could be useful – although Turkey is already supplying them to Ukraine.

Ukraine most likely already has large stocks of small firearms such as basic rifles and AK-47s because Kyiv will have been preparing for a while, Prof Chalmers added.

Will help from NATO prevent Russia from taking over Ukraine?

NATO allies have pledged to stop Moscow from imposing a puppet regime in Ukraine to then claim it as its own.

But, Prof Chalmers said ultimately Russia has one of the most capable armies in the world and Ukraine cannot match it, despite NATO help.

“The two sides are very ill-matched, Russia has a massive superiority in firepower and the Ukrainians are weak comparatively,” he said.

He said there will likely be an initial phase where Russian and Ukrainian troops are fighting on the ground in Donbas and potentially around Kyiv but Russia will take control of the air very quickly.

“It will quite quickly move beyond that conventional campaign that will look more like ourselves fighting the Taliban – very different terrain and people but it’s going to feel more like an insurgency against an occupying army,” he said.

“As we’ve seen in Afghanistan the most sophisticated army in the world can be defeated by a determined but pretty poorly armed resistance.

“Where the Ukrainians have an advantage is they’re fighting for their own territory and all that massive firepower is going to be hard to use as an occupation force, as NATO found out in Afghanistan.

“You can have all the technology you want but it’s very difficult to control a country if even a significant minority are willing to fight – and I think they will in Ukraine.

“We can help them to fight a very asymmetric campaign but if they move to an insurgency phase the Ukrainians will be defeated very quickly.”