The tide in several Western countries is gradually turning toward asserting more sovereignty. If Israel’s leaders study and understand this development it can open up important perspectives for policy making.Some expressions of the trend are major. US President Donald Trump emphasizes sovereignty issues – sometimes in a brutal way. “America First” is a sovereignty message, as is implementing more stringent border controls by excluding undesirable and illegal immigrants. During his election campaign, Trump stated that people with antisemitic opinions should not be allowed to immigrate to the US. Major American Jewish organizations have however failed to promote this idea since Trump’s election to office.In the UK the majority vote for Brexit was based on the same desire for sovereignty. Many of those who voted to leave the European Union were largely motivated by their opposition to the EU’s free movement of citizens of member countries. It seems that Eastern European immigrants worried Brexit supporters more than Muslims. After the three terrorist attacks this year by Muslims in London and Manchester, UK citizens may well regret that previous governments were not more selective in their entry policies.In the past the UK did not join two EU sovereignty-reducing programs: the euro common currency and the Schengen Area which abolished internal border controls.In practice, the Schengen group poorly protected their external borders.Czech President Milos Zeman proposed that his country should hold a referendum on EU and NATO membership. He is in favor of staying in both organizations, but felt that citizens of his country should have an opportunity to express themselves on the issue.Beyond this, there are also smaller movements to abandon EU membership. In the Netherlands, for instance, almost a quarter of parliamentarians belong to parties that want to leave the EU. Sovereignty was also demonstrated in the refusal of some EU members to accept Syrian and other refugees that Brussels wanted to impose on them. Hungarian Prime Minister Viktor Orban was the first and most vocal opponent. In the final round of the French presidential elections Marine Le Pen, who wants to reestablish French border controls, received a third of the votes. A study by the leading Italian investment bank Mediobanca showed that it would be advantageous for Italy to leave the euro and reestablish the lira.There have also been smaller expressions of sovereignty, which were less publicized internationally. In March of this year, Dutch Prime Minister Mark Rutte refused to allow the plane of a Turkish minister – Turkey is a NATO ally – to fly to Rotterdam. The minister had intended to appeal to Dutch Turks with dual nationality to vote in a Turkish referendum to support greater power for Turkish President Recep Tayyip Erdogan.Peter Altmaier, the head of German Chancellor Angela Merkel’s office, said that in view of derogatory remarks against Germany from leading Turkish politicians Germany was considering prohibiting their entry.From time to time the Netherlands bans entry of radical Islamic preachers or “hate imams” as they are commonly known in the country. In October 2016, for the first time, Belgium expelled a Muslim hate preacher.This fact was even more remarkable because this imam held not only Moroccan but also Dutch nationality. At the beginning of May 2017, Denmark refused entry to six hate preachers, five Muslims and one Evangelical Christian. This was based on new legislation passed in 2016.Israel has been suffering from foreign interference in its affairs and large-scale incitement against it. Part of this is antisemitic, such as the activities of boycott promoters who exclusively target Israel. That is in line with the antisemitism definition of the International Holocaust Remembrance Alliance. The discriminatory targeting of Israel was for instance explained in remarks by Curtis Marez, the president of the American Studies Association (ASA). He did not dispute that countries including some of those in Israel’s region have comparable or worse human rights records than Israel. Instead he said, “One has to start somewhere.”In Israel, too, there have recently been some examples of assertion of sovereignty. Earlier this year the Knesset accepted a law barring entry to foreign boycott activists. One has to see how this law is applied in practice.It should be extended to various other anti-Israel hate mongers. Just one example of such hate mongers: The ADL published in 2013 a list of the 10 most anti-Israel organizations in the US. The rhetoric some of these groups employ includes comparisons of Israeli leaders to Nazis, or describing the Gaza Strip as the new Auschwitz, calling for the dismantlement of the State of Israel, or expressing support for terrorist groups that seek Israel’s destruction.Another example of exercising sovereignty was Prime Minister Benjamin Netanyahu’s refusal to receive German Foreign Minister Sigmar Gabriel due to the fact that the latter met with the anti-IDF organization Breaking the Silence. Netanyahu’s office has stated that he will not meet foreign visitors “who on diplomatic trips to Israel meet with groups that slander IDF soldiers as war criminals.”Time is on Israel’s side in moves to assert sovereignty.Terrorist attacks like the three this year in the UK will lead to increased restrictions on who is allowed entry into democratic countries. What Israel needs is a systematic focus on the issue of how to better assert sovereignty. Simultaneously it must develop public diplomacy to rally support for moves expressing greater sovereignty.The author is emeritus chairman of the Jerusalem Center for Public Affairs. He was given the Lifetime Achievement Award by The Journal for the Study of Antisemitism, and the International Leadership Award by the Simon Wiesenthal Center.