AK: Yes, I am aware.  However, they way I am expressing this, classified information are "secrets" while classified information communicated to another is "confidential" information.  It wasn't a secret that the US (or Trump in case any  orange people still confuse the two) created or developed.  In other words it wasn't Trump's secret he was obligated to not disclose.  It was another nation's secret.  It would be bad to one degree if Trump had let Russia in on a secret that the US "owned" but its bad to additional degrees that Trump let Russia in on a secret "owned" by another nation.
Think of it like having your doctor or lawyer giving out personal information you provided in the strictest confidence.  It would be bad if you let it out but it is worse when your doctor or lawyer lets it out.