Protecting military secrets starts with the people trusted to keep them.

British counterterrorism police arrested a 41-year-old U.S. Army soldier near Gloucester on Tuesday on suspicion of obtaining or disclosing protected information and assisting a foreign intelligence service. The allegations concern Russia, according to a Metropolitan Police statement.

Officers were searching two locations in Gloucestershire. The soldier remained in custody at a London police station.

The investigation involves British authorities, the FBI and U.S. Army counterintelligence investigators—the people charged with catching spies and protecting Army secrets.

Brig. Gen. Sean Stinchon, who commands Army Counterintelligence Command, described the suspect as a senior soldier entrusted with sensitive information. He warned that “insider threats are real and persistent.”

That is the vulnerability no perimeter fence can fix: someone already trusted with access.

Police have not released the soldier’s name, rank or unit. Their statement announced an arrest, not charges. The allegations remain unproven.

One distinction matters as reports of threats against American aircraft in Britain pile up: Police explicitly said this investigation is separate from other ongoing counterterrorism investigations.

These are serious allegations. They are not evidence that every security scare in Britain belongs to the same plot.