BRUNSWICK — I believe that this is a defining moment in U.S. history. With the stream of new policies threatening to wash away the rights of refugees and other immigrants, America is in the midst of a full-blown identity crisis.

Many patriotic and caring Americans are asking, “What can I do?” The first step is to make sure more of our fellow citizens understand who we are. In Sun Tzu’s “Art of War,” the ancient master of strategy famously advised, “Know yourself, and know your enemy, and in a thousand battles you will not be defeated.” Human history has often demonstrated that the harder of these tasks is to know yourself, and this appears to be the case for America today.

With his executive order blocking Syrian refugees and travelers from other several Muslim-majority nations (in both its original and revised form), his ultimatum on sanctuary cities and his push for building a wall on the Mexico-U.S. border, the president is doing nothing less than attempting to redefine who we are. If there were a clearer, broader understanding of our rightful and historical role as a beacon of hope for immigrants, then President Trump wouldn’t be getting any traction with his rejection of our country’s tradition of openness to, and compassion for, outsiders. It would be a nonstarter.

Along with many other veterans, I find the president’s moves distressing, and I believe that if left unchecked, they will make this country a far less admirable place for our children and grandchildren. I’m a recently retired Navy commander who logged 327 combat missions in Bosnia, Kosovo, Afghanistan and Iraq. During my more than three decades of service, I was guided by the conviction that I was helping to defend not just America or Americans, but American ideals. The very ideals now under threat, not from a foreign adversary, but from a misguided political leader playing to fear.

The good news is that the president’s moves have faced protests in the streets, rejection in the courts and denunciations in Congress. It is not surprising that there is a great deal of opposition. Many Americans need to look only a rung or two down their own family’s ladder to recognize that these actions do not reflect the nation that welcomed their parents or grandparents.

The opposition, however, should be larger; it should be overwhelming. But then, it is not unprecedented for Americans to lose touch with their ideals, to “forget themselves,” during times of war. The Trump administration’s hard line against refugees and immigrants brings to mind our nation’s most shameful moments, the most well-known being the interment of more than 110,000 American citizens of Japanese ancestry during World War II. Lesser-known events, but ones stemming from the same dark stream of nationalism, prejudice and xenophobia, were the attacks on German Americans during World War I, the Mexican Repatriation Act following the economic collapse in 1929 and the Eisenhower-era “Operation Wetback” in 1954.

More recently, we need only look to America’s overreactions to the 9/11 attacks. The U.S government set up CIA “black” interrogation sites and sanctioned torture for the first time in our nation’s history. Following a lengthy national debate, government leaders halted most of these inhumane practices. The consensus is that these policies did more harm than good to U.S. national security objectives.

Yet those mistakes continue to do damage, and there is never a guarantee that a break with American ideals won’t become a permanent rupture. Are we a nation that will no longer accept the tired, the poor, and the huddled masses yearning to breathe free? If the answer is no, then in a few years we will have to look at the Statue of Liberty as a symbol of what America used to be.

If you believe, as I do, that we are a nation that should uphold those ideals, then let your voice be heard. Write or call your representatives in Congress. Join or organize a protest. Get involved and persuade others to do the same. This is our generation’s moment to stand up and situate ourselves squarely on the right side of history.

This political battle will define the very heart and soul of America. At the end of this era, I wish to be counted among those who chose to fight against fear, hate and prejudice. I have hung up my flight suit and placed my medals in a shadow box, but I’m ready to serve.