In one of the strongest signs of public frustration over controversial security bills likely to be passed by lawmakers next month, thousands of people surrounded the Diet building Sunday afternoon to protest their enactment and call for the resignation of Prime Minister Shinzo Abe.

Organized by a union of three different anti-war citizens’ groups, Sunday’s rally was arguably the most massive in a string of similar protests in recent months.

The organizer claimed as many as 120,000 people gathered around the Diet building, with about 200 protest rallies held nationwide.

Meanwhile, NHK, quoting unnamed police sources, reported the Metropolitan Police Department estimated that only 30,000 protesters gathered around the Diet. A police spokesman declined to comment when contacted by The Japan Times.

Ken Takada, one of the chief protest organizers, said the turnout echoed what is widely remembered as the nation’s biggest civil demonstration ever near the Diet in 1960.

That demonstration was against the revision of the Japan-U.S. security treaty. Police said 130,000 people turned out to that event, but organizers estimated it was 300,000.

On Sunday, a sense of immediacy appeared to pervade the raucous rally with the bills, currently under deliberation in the Upper House, expected to be enacted mid-September.

The security legislation will greatly expand the scope of Japan’s logistical support for any U.N.-authorized force and allow the country to exercise the right to collective self-defense with an ally, likely the United States, if an event critically threatens Japan’s national security.

Protesters maintain the move, long banned under the postwar Constitution, is unconstitutional and that the bills could eventually drag Japan into an unwanted war.

The government, meanwhile, says the legislation is vital to strengthening the Japan-U.S. military alliance and protecting the country from growing global threats such as those from North Korea.

Participants, ranging from the young to the elderly, braved the rain to sing songs, shout slogans and wave banners demanding the bills’ abolition and Abe’s resignation.

One protester, 75-year-old Michio Yamada, said he was determined to thwart the bills’ passage and prevent Japan from ever engaging in a war again for the sake of his five teenage grandchildren.

Yamada, who at 5 years old witnessed the Great Tokyo Air Raid in 1945, said he was still haunted by the horrifying scene in which his neighbors in the Ryogoku area of northeast Tokyo jumped into the Sumida River in a desperate bid to escape the deadly blast and ensuing inferno.

“With the advance of technologies (over the past seven decades), war is likely to be more deadly than it used to be,” Yamada said. “In this age of nuclear weapons, you will never know how massive a death toll is going to be. The danger is far bigger than before. “We should never let it happen again,” he added.

A 38-year-old mother, who only gave her first name, Naoko, said she was worried about possible consequences of the bills that her children would have to face.

The bills, which she said ran counter to the pacifist policies Japan has adhered to over the past 70 years, could see her children embroiled in wars.

“Instead of enacting such pro-war bills, I want Japan to exert leadership roles in facilitating world peace as has done (since World War II),” she said.

Translator Hiromi Miyasaka, 49, said she resented the way the government was trying to steamroll the bills into enactment despite widespread public concerns.

“The way the government brushes aside public worries . . . it’s as though Japan is slipping back into its pre-World War II state,” she said.