It is claimed that a number of soldiers who have expressed their intention to travel have been identified and persuaded against the idea in interviews with their chain of command.
Last week Lieutenant General James Swift, the Chief of Defence People, issued a directive down the chain of command to all personnel against going to Ukraine.
This was done “in concert” with the discovery of the teenage Coldstream Guardsman’s departure, it is understood.
It came after Liz Truss, the Foreign Secretary, expressed her support for UK volunteers heading to fight for Kyiv, saying she “absolutely” backed Britons who wanted to join the Ukrainians’ “struggle”.
“That is something people can make their own decisions about. The people of Ukraine are fighting for freedom and democracy, not just for Ukraine but for the whole of Europe,” she said last month.
Liz Truss backtracks
On Wednesday she backtracked on the idea, insisting: “The travel advice from the United Kingdom is not to go to Ukraine… There are better ways of helping the efforts in Ukraine, namely donating to the (DEC) appeal.”
Ms Truss said her previous remarks had meant only to express support for the Ukrainian cause and make clear that those fighting in self-defence were engaging in a just war.
Admiral Sir Tony Radakin, Chief of the Defence Staff, had issued a rebuke to Ms Truss at the weekend, declaring: “We’ve been very clear that it’s unlawful as well as unhelpful for UK military and for the UK population to start going towards Ukraine in that sense.”
He added: “Support from the UK, support in whatever way you can. But this isn’t really something that you want to rush to in terms of the sound of gunfire. This is about sensible support based in the UK.”
Any personnel found to have gone AWOL may be subject to disciplinary and administrative punishment by the military, but are judged on a case-by-case basis.
Army insiders pointed out that some reservists may have had legitimate work reasons to have been in Ukraine when the invasion erupted.
Boost defence spending
It is not illegal for troops on leave to travel to eastern European countries such as Poland to help with humanitarian efforts.
Ms Truss warned on Wednesday that the West had not “spent enough on defence for a number of years and we have seen a buildup of military capability from Russia in terms of both technology and numbers”.
In the US to meet with her American counterpart Antony Blinken, Ms Truss suggested that in addition to conventional defence, the UK needed to “step up our efforts in areas like information”.
She added: “The UK abandoned its information unit at the end of the Cold War and the Russians didn’t abandon their information unit.”
A Ministry of Defence spokesman said: “All service personnel are prohibited from travelling to Ukraine until further notice. This applies whether the service person is on leave or not. Personnel travelling to Ukraine will face disciplinary and administrative consequences.”