Liam Sneddon and two associates are said to have been arrested in May 2022 after a parcel containing a Glock 17 firearm was discovered.
According to the Daily Record, the 34-year-old was remanded in custody after he pleaded guilty at the High Court in Glasgow to a charge of being involved in serious organised crime.
Sneddon launched a social media appeal three months before his arrest pledging to join the efforts in war-torn Ukraine to help those impacted by the conflict.
In a Facebook post dated 28 February, Sneddon wrote: "I am running a bus this week into Ukraine with supplies and taking women and children out to places of safety. Also Scotland is now accepting Ukraine refugees."
But two months later, he was reportedly arrested after US federal agents inspected a parcel due to be sent to an address in Stirlingshire in Scotland and found the handgun and a manual inside.
The court heard how the weapon was seized by agents and replaced by a placebo package containing clandestine recording devices, which was delivered instead.
This parcel was taken to the address where Steven Richardson, 47, and another man were. Sneddon and associate 40-year-old Paul Kirwan reportedly drove in the travel agent’s car to woods in Lanarkshire, where they were met by Richardson.
Photos from a camera concealed in the package showed images of Sneddon and Kirwan trying to open it, both wearing balaclavas and latex gloves, before officers from the National Crime Agency arrested them.
The charge stated it was Kirwan who arranged the purchase of the Glock, and prosecutors accepted that Sneddon believed he was buying cannabis from the US, rather than a gun.
All three men pleaded guilty, and sentencing will take place in Edinburgh on 2 June.
