In weird Torygraph ... news? ... that might be the rare non-Russian disinfo about Russia's warlike activities:

Russia is sending migrants through underground tunnels from Belarus into Europe as part of its hybrid war on the West.

Belarus, a Russian puppet state led by dictator Alexander Lukashenko, has used specialists from the Middle East with “a high level of expertise” to design the tunnels, Polish officials have told The Telegraph.

[...] And while experts say it is hard to be sure which groups were involved, they have suggested Kurdish fighters, Islamic State and Iranian-backed proxies as potential culprits.

To me, the claim seems a lot like a paranoid xenophobic fantasy of somebody who feels that it's presence of immigrants that's the prob;em, and since they believe that Lukashenka is a Bad Person(tm), he would, obviously, do things that feel bad to the paranoid fabulist. It's also possible that the paranoid ideation is not of the creator's, but of the target audience's.

In the real life, Belarus has dispatched migrants to the Polish border, but the operations' value for Lukashenka is not the migrants' presence in Poland, but the high-profile press events about them seeming like crossing, or about to cross the border. Covert border-crossings would make the whole affair pretty much worthless for him.

Furthermore, even if such crossings were to take base, the jump to attribution seems awfully dubious, and may come out of a standard Western paranoid xenophobe's fantasies about Muslims being Designated Bad People, or, as above, may be carefully designed to appeal to Western paranoid xenophobes who have such prejudices against Muslims.

Archived Torygraph article, because bad actor: https://archive.is/BTM5j