As a public diplomat and (until recently) spokesman of the department of state, I was responsible for explaining the national security policy of the United States to the American people and populations abroad. I am also a retired military officer who has long believed that our civilian power must balance our military power. Part of our strength comes from international recognition that the United States practises what we preach. Most of the time, we do. This strategic narrative has made us, broadly speaking, the most admired country in the world.

To be clear, Private Manning is rightly facing prosecution and, if convicted, should spend a long, long time in prison. Having been deeply engaged in the WikiLeaks issue for many months, I know that the 251,000 diplomatic cables included properly classified information directly connected to our national interest. The release placed the lives of activists around the world at risk.

Julian Assange and others have suggested that the release of the cables was to expose wrongdoing. Nonsense.

While everyone can point to an isolated cable, taken as a whole, the cables tell a compelling story of "rightdoing" – of US diplomats engaged in 189 countries around the world, working on behalf of the American people, and serving broader interests as well. As a nation, we are proud of the story the cables tell, even as we decry their release.

But I understood why the question was asked. Private Manning's family, joined by a number of human rights organisations, has questioned the extremely restrictive conditions he has experienced at the brig at Marine Corps base Quantico, Virginia. I focused on the fact that he was forced to sleep naked, which led to a circumstance where he stood naked for morning call.

Based on 30 years of government experience, if you have to explain why a guy is standing naked in the middle of a jail cell, you have a policy in need of urgent review. The Pentagon was quick to point out that no women were present when he did so, which is completely beside the point.

The issue is a loss of dignity, not modesty.

Our strategic narrative connects our policies to our interests, values and aspirations. While what we do, day in and day out, is broadly consistent with the universal principles we espouse, individual actions can become disconnected. Every once in a while, even a top-notch symphony strikes a discordant note. So it is in this instance.

The Pentagon has said that it is playing the Manning case by the book. The book tells us what actions we can take, but not always what we should do. Actions can be legal and still not smart. With the Manning case unfolding in a fishbowl-like environment, going strictly by the book is not good enough. Private Manning's overly restrictive and even petty treatment undermines what is otherwise a strong legal and ethical position.

When the United States leads by example, we are not trying to win a popularity contest. Rather, we are pursuing our long-term strategic interest. The United States cannot expect others to meet international standards if we are seen as falling short. Differences become strategic when magnified through the lens of today's relentless 24/7 global media environment.

So, when I was asked about the "elephant in the room," I said the treatment of Private Manning, while well-intentioned, was "ridiculous" and "counterproductive" and, yes, "stupid".

I stand by what I said. The United States should set the global standard for treatment of its citizens – and then exceed it. It is what the world expects of us. It is what we should expect of ourselves.