From Paris to Pittsburgh, Jews are under siege as the scourge of violent antisemitism reaches depths not seen since World War II. Just this week, FBI Hate Crime data was released, which showed that Jewish Americans were subject to 60% of religiously motivated hate crimes in 2017, despite being just 2 percent of the US population, a 37% increase over 2016.For the last 12 months we have been on a mission to assess the depth, manifestation and trajectory of antisemitism in key European counties as well as the physical security of the Jewish diaspora, personally commissioned by Ronald Lauder, president of the World Jewish Congress.While we left New York City last January for London, Paris, Brussels, Berlin, Budapest and other points east, it was when we were in Kiev, on October 27, that the deadly and dastardly attack against Pittsburgh’s long-standing Jewish community erased the distance and some of our notions about differences between Paris and Pittsburgh.As part of our fact finding mission, we have met with scores of government policy makers and diplomats, police and intelligence officials, rabbis and students, as well as academics and leaders of the myriad Jewish organizations in the UK, France, Germany, Belgium, Austria, Hungary and Ukraine. And we’ve walked in the footsteps of martyred Jews in Dachau, Babi Yar and the Paris Hypercacher Kosher supermarket, among others.We have also analyzed country specific survey data and statistics and met with leadership of US based watchdog groups like the Anti-Defamation League, American Jewish Congress and World Jewish Congress.What have we learned?1. In Europe, the threat of physical violence against Jews is the highest it has been since the demise of Nazi Germany, more than 73 years ago. In addition, though it is distributed unevenly and expresses itself differently in each country, the sad reality is that antisemitism is on the rise and is here to stay. Soon to be released data tracking physical violent assaults against Jews in France in 2017 will show a multi-fold increase over what was an already too high number in 2016.2. Antisemitism manifests itself in Europe in three primary ways. Two of these, polar opposites, are threatening, but have triggered limited physical violence. They are extreme left-wing progressive anti-Zionism, that while different from antisemitism, at a practical level often bleeds into antisemitism (see the UK’s potential next Prime Minister, Jeremy Corbyn). And there is far right white Nationalism/Neo-Nazism, which has lay relatively dormant since the end of WWII but is on the rise in Germany (see the Alternative for Deutschland [AfD] party) and Central Europe.The third stream of antisemitism, which has been deadly, emanates from diaspora Muslim populations in Western Europe, both second and third generations citizens and new asylum seekers. They have been poorly assimilated due to a combination of ineffective government policies and real socio-economic grievances, as well as their own resistance to more secular integration into European societies. This threat, which has proven deadly over the last few years in Brussels, Copenhagen and Paris to name a few, has some overlap with a phenomenon that we are quite familiar with – a terrorism threat driven by those radicalized in the West.3. The atrocity in Pittsburgh demonstrates that lone actors can be spontaneously mobilized to violence against Jews anywhere, including here, at home. And this event should be a clarion call to action.While expressions of solidarity with victims as well as tweets and press releases condemning specific antisemitic acts are understandable, they are no longer sufficient. The dashboard is blinking red for a devastating attack against Jews in Europe and America.What can be done?We believe that there are real world actions that can better protect Jewish minorities, both here and abroad. Some of our insights come from lessons learned in Europe and are applicable here, at home. Other recommendations are based on our law enforcement and counterterrorism experience in New York City Police Department and are useful abroad.First, every Jewish institution needs to develop a comprehensive security plan. Active shooter drills, functioning alarm systems and the use of CCTV cameras should be components of this enhanced security regime. Importantly, in Europe, access control to Jewish institutions is of the highest priority and virtually all of the Jewish institutions that we visited in Europe had installed a “double door” system, where visitors could not enter the institution until they had been cleared and the door behind them had locked. Although trained armed guards can be helpful, they are not a panacea and frankly, are not a viable option for most institutions, given the cost. One individual should be designated as the point of contact for law enforcement and responsible for the security mission.Secondly, we cannot over emphasize the necessity of developing a close relationship with local law enforcement. Given the heightened threat level, the police have a special obligation to provide unique attention to Jewish institutions, especially at high traffic times like Friday night and Saturday morning services. The NYPD for years has provided patrol resources that serve as protection and deterrent to synagogues in New York City and frankly, other houses of worship as well, depending on the evolving threat. The police can be helpful in developing a security plan.Third, one strategy that is quite common in the United Kingdom and France and is worth considering implementing in the US is the use of trained volunteers from within the Jewish community to provide yet another layer of protection for Jewish institutions. These volunteers, who undergo training on how to recognize surveillance as well as basic personal defense are valuable and a cost-effective force multiplier that Jewish institutions and communities can organize on their own. These volunteers serve a key role in a layered defense, between police and the institution.Lastly, federal governments have a role to play. In 2005, the US Department of Homeland Security created the Nonprofit Security Grant Program to assist institutions by providing funding for them to invest in protecting themselves. We think this should be continued and potentially augmented in the US and needs to be significantly boosted in countries, like France.The rise of social media, lingering angst over the financial meltdown of 2008 and the spread of intolerant ideologies have all been identified as root causes of the rising tide of antisemitism. Regardless of its root cause(s) and despite the best intentions of many, the vile phenomenon of violent antisemitism is unfortunately here to stay and thus, appropriate protective measures must be taken.Raymond W. Kelly is the former Police Commissioner for the City of New York. Mitchell D. Silber is the former Director of Intelligence Analysis at the New York City Police Department. David Cohen is the former Deputy Commissioner of Intelligence at the New York City Police Department.