JERUSALEM (AP) — Israelis stood still on Thursday for a nationwide moment of silence in remembrance of the 6 million Jewish victims of the Holocaust, as a two-minute siren wailed across the country and the nation paid respects to those systematically killed by Nazi Germany and its collaborators in World War II.

As every year on Holocaust Remembrance Day, buses and cars halted on streets and highways and Israelis stepped out of their vehicles, standing with heads bowed in solemn remembrance.

The somber day is also marked by ceremonies and memorials at schools and community centers. Restaurants and cafes in the ordinarily bustling streets of Tel Aviv shutter, and TV and radio stations play Holocaust-themed programs. Dignitaries laid wreaths at Yad Vashem, the national Holocaust Memorial in Jerusalem.

A third of the world's Jews were murdered in the Holocaust. Israel was established afterward in 1948, and hundreds of thousands of survivors fled to the Jewish state.

On Wednesday evening, Prime Minister Benjamin Netanyahu spoke at a Holocaust memorial ceremony at Yad Vashem and warned that archenemy Iran should not test Israel amid rising tensions in Syria.

"Events of recent days teach that standing up to evil and aggression is a mission imposed on every generation," Netanyahu said.

"Today as well, a murderous regime threatens us, threatens entire world peace, this regime explicitly declares that it intends to annihilate us, the Jewish state," he said, alluding to Iran.

Netanyahu compared the 2015 nuclear deal between world powers and Iran to the appeasement of Adolf Hitler in the run-up to World War II. He said the agreement "released the Iranian regime from its chains and since has devoured country after country, similar to what happened in Europe in the 1930s."

Israel regards Iran as an existential threat because of its nuclear and ballistic missile programs and support for anti-Israel organizations such as the Shiite militant group Hezbollah in Lebanon and Palestinian militant groups Hamas and Islamic Jihad.

Tehran insists that its nuclear program is for peaceful purposes only.