The country’s long-ruling Liberal Democratic Party is reeling under the shock of the loss of its majority in the lower house of the parliament, or diet, just as the government is protesting North Korean troops in Russia.

The election results mean that Japan’s prime minister, Shigeru Ishiba, must focus on getting enough seats for his Liberal-Democrats to control a majority of the 465 seats in the lower house, which elects the prime minister.

Mr. Ishiba called the elections a month ago after his election by the lower house as prime minister in high hopes his party would gain still more seats and confirm his grip over the government. The ruse has backfired, plunging Japan into a political crisis that diverts attention away from worries about North Korea, which views Japan as an enemy in the same category as South Korea and America.

The chief secretary of Mr. Ishiba’s cabinet, Yoshimasa Hayashi, stated that the government was “monitoring with serious concern North Korea’s dispatch of troops to Russia,” but Mr. Ishiba now is looking for new coalition partners among minor parties holding small numbers of seats in the lower house. The LDP has not been in such a predicament since a left-leaning coalition held power between 2009 and 2012.

For Mr. Ishiba, the concern now is not the danger posed by North Korea or its allies, Russia and Communist China, but simply clinging to office while his party suffers from the scandals of slush funds that members of the LDP and its partner, the Buddhist-backed Komeito Party, diverted for their personal use.

“The dismal results underscored deepening distrust in the ruling Liberal Democratic Party,” said Japan’s Kyodo news agency, blaming the slush funds scandal for what it called “a seismic shift in the support that enabled it to return to power in 2012 after a spell in opposition.”

The political crisis is also likely to cast a shadow over Mr. Ishiba’s idea of broadening the role of Japan’s military establishment, known as “self-defense forces,” by weakening or doing away with Article 9 of Japan’s postwar constitution banning Japan from sending its forces overseas.

He also called for making Japan “an equal partner” with its American ally, revising their longstanding defense treaty as well as an accompanying  status-of-forces agreement that gives  the Americans control over soldiers accused of crimes against Japanese.

The impact of these reforms would have been to project Japan again as a regional military power reminiscent of the era before World War II. In this turn of events, Japan would be able to support Washington against rising Chinese power and also  stand up more effectively against North Korea while strengthening ties with South Korea.

The latest elections, however, put all those dreams on hold. Now Mr. Ishiba has to worry about the possible resurgence of the leader of the Constitutional Democratic Party, Yoshihiko Noda, whose party — which is center left — now holds 148 seats in the lower house.

Having served as prime minister for the three years in which the LDP was out of power,  Mr. Noda hopes to challenge the LDP in a long shot bid to lead the government again.

Although he supports the alliance with Washington, Mr. Noda opposes revision of the constitution or any other steps that would increase the size of the armed forces. His own party and leaders of minor parties are sure to engage in spirited debate, most of it having little to do with defense.

“The developments are similar to those in some European countries,” said a Kyodo commentary. “Far-right or far-left political parties have gained momentum amid mounting frustration with mainstream powers seen as favoring elites and the wealthy.”