In a February 2002 news conference, Secretary of Defense Donald Rumsfeld was asked about evidence linking Iraq to supplying terrorist groups with weapons of mass destruction.

Rumsfeld famously observed “we know there are known knowns… there are also known unknowns… but there are also unknown unknowns—the ones we don’t know we don’t know…”

As 2016 comes to an end, Germans should be disturbed by bookend events of the year that are most revealing about their Chancellor, Angela Merkel, who refuses to accept one-time unknown unknowns as known knowns.

Under Merkel’s leadership, Germany opened its doors to over one million Muslim immigrants. More are to follow during 2017.

This gave rise to obvious known knowns, such as where to house immigrants, how to help them transition into German society, how to fund the endeavor, etc. There were unknown knowns, including whether immigrants would successfully assimilate into German society. But unknown unknowns always remained a possibility, only capable of being addressed after transitioning into known knowns.

Arguably, if Merkel lacked any idea opening the floodgates to Muslim immigration would create a sea in which Islamic extremist terrorists could freely swim and/or be radicalized, such could have, initially, been deemed an unknown unknown.

But 2016 should have enlightened her as this unknown unknown became a known known.

As Germans in the city of Cologne welcomed 2016 with a New Year’s celebration, reports began pouring in that women were being raped, assaulted or robbed by Muslim males. Police estimate at least 2,000 Muslim males were involved in more than 1,200 such attacks, most of which went unsolved. However, German officials undertook every effort to keep this rape epidemic quiet lest it cast Merkel’s mass Muslim immigrant program in a bad light.

Since news of these attacks leaked out, Cologne’s mayor now seeks to repair the city’s image. She has planned a mass media show in the main square for New Year 2017. Obviously, in recognition of the known known that Muslim men may attack women, she will deploy 1800 police officers — a thirteen-fold increase over last New Year’s — along with armored vehicles, helicopters and mounted police. This is quite a commitment of security assets for a problem the German government does not even choose to admit exists.

While these security precautions represent a city mayor acting responsibly to prevent or limit violence, it is irresponsible that she refuses to admit the real source for her concern. She chooses to view it in terms of some nefarious criminal element rather than in terms of an influx of supposedly moderate male Islamic followers allowed into the country who firmly believe the Quran entitles them to abuse all women.

While Merkel turned a blind eye to Cologne, she must now face the reality of the December 19th terrorist attack in Berlin. In response to initial reports suggesting the terrorist was a Muslim migrant, Merkel offered the following statement: “I know it would be especially hard to bear for all of us if it should be confirmed that the person who committed this act sought protection and asylum in Germany. This would be especially despicable toward the many, many Germans who are daily engaged in helping refugees…”

What is despicable is Merkel’s refusal to have prevented or limited the threat to the public in the first place by acting upon the threat posed by a Muslim migrant crime wave.

Evidence indicates a Tunisian Muslim immigrant drove a tractor-trailer into a crowd of Christmas shoppers, killing twelve and injuring 50. Ironically, the day of the attack, Merkel attended a “Migrants Day” celebration.

In the wake of the Berlin attack and numerous crimes committed by Muslim immigrants, it should be obvious to any reasonable person that what Merkel may well have considered an unknown unknown before 2016—i.e., whether Muslim immigration would negatively impact domestic security—has now entered the realm of a known known.

Despite all that is now known, despite Germany suffering several ISIS-inspired attacks and foiled terrorist plots, despite the fact most involved Syrian or Afghani migrants, Merkel still refuses to acknowledge terrorist activity in any way relates to her unbridled Muslim immigration policy.

While the Berlin attacker may be viewed as a Muslim extremist, the Cologne attackers were supposed moderates. This should tell us something about the line separating the two. Ideologically, the line is thin, easily crossed by supposed moderates as both groups believe the Quran gives them a license to engage in criminal activity against non-believers.

One need only read the Quran to understand Muslim males are permitted to behave badly towards all women—particularly infidels. An educational pamphlet recently published in moderate Turkey advises newlyweds that abuse of women is a male right women need anticipate.

While the German government keeps quiet about Muslim migrant crime, law enforcement groups seek to give it focus. A police union recently published an open letter criticizing the lack of governmental action to maintain law and order, despite repeated briefings to officials on the issue.

Not only has the government apparently abandoned the police, police have become politically expendable as well. After the frustrated head of the German Police Union lamented “criminals are using open borders,” a Merkel political supporter of her immigration policy called the comment “disgusting and stupid as one can get.”

Meanwhile, leaders of the Ruhr Muslim community—a region encircling Cologne—boast, “The police will not win a war with us because we are too many.” Muslim assimilation has been an abject failure there. It is a spear pointed at the heart of Cologne’s non-Muslim community. New Year’s 2017 will be but a two-day security test. Eventually, however, that spear will draw infidel blood.

For locals, as unknown unknowns about Muslim migrants transition to known knowns, blindly ignored by their civilian leadership, another known known emerges. It is the fear of a growing Muslim population unfettered by local laws. Sadly, Germany will prove unable to deal with them because they will have, as boasted, become “too many.”

Lt. Colonel James G. Zumwalt, USMC (Ret.), is a retired Marine infantry officer who served in the Vietnam war, the U.S. invasion of Panama and the first Gulf war. He is the author of “Bare Feet, Iron Will–Stories from the Other Side of Vietnam’s Battlefields,” “Living the Juche Lie: North Korea’s Kim Dynasty” and “Doomsday: Iran–The Clock is Ticking.” He frequently writes on foreign policy and defense issues.