Japan accused critics of its annual dolphin hunt – including U.S. Ambassador Caroline Kennedy – of being hypocrites for not lamenting the killing of cattle and chickens in their countries for food.

The southwest fishing town of Taiji finished its annual roundup of bottlenose dolphins Tuesday, a longheld tradition that Kennedy called “inhumane” in a message on Twitter.

Japanese fishermen Tuesday trapped 250 dolphins in a cove using nets and killed about 40 of the animals for eating by severing their spines. About 50 were kept alive for sale to aquariums and the rest were set free, according to Sea Shepherd, an environmental group known for its anti-whaling activities.

Japanese officials and others were surprised that a diplomat from an ally would lash out at a traditional cultural food. Chief Cabinet Secretary Yoshihide Suga told reporters at a news conference Monday that marine mammals, including dolphins, were “very important water resources.”

“Dolphin fishing is one of traditional fishing forms of our country and is carried out appropriately in accordance with the law. Dolphin is not covered by the International Whaling Commission control and it’s controlled under responsibility of each country.”

Taiji Mayor Kazutaka Sangen said Kennedy is attacking ordinary fishermen.

“We have fishermen in our community and they are exercising their fishing rights,” he said. “We feel that we need to protect our residents against the criticisms.”

A State Department official who asked not to be named because it is against policy to discuss the matter publicly said Kennedy proposed issuing her statement last week. The final wording of her tweet was the result of collaboration between Kennedy and other embassy officials and reflects official U.S. policy, the official said.

Masayhisa Sato, a Japanese lawmaker, suggested Kennedy acted inappropriately in her role as an ambassador to criticize a hunting tradition in a host country that she finds distasteful.

“I wonder whether it’s appropriate for ambassador to comment on this,” Sato said.

In office just two months, Kennedy took to the social media messaging system Twitter over the weekend to condemn the hunt portrayed by opponents as needlessly cruel.

“Deeply concerned by inhumaneness of drive hunt dolphin killing. USG opposes drive hunt fisheries,” Kennedy tweeted in both English and Japanese. “USG” refers to the U.S. government.

Japanese who spotted the Tweet responded.

“The drive hunt is a traditional fishery that was established long before the foundation of the United States of America,” said one message posted in response.

“Isn’t it inhumane to kill millions of cows and sheep for consumption?” asked another.

The Taiji hunt, in which hundreds of dolphins are driven into a small cove and killed, was the subject of a graphic documentary in 2009 that won an Academy Award.

Kennedy’s dolphin tweet could complicate relations between two vital allies, said Robert Dujarric, director of the Institute of Contemporary Asian Studies at Temple University of Japan, in Tokyo.

“There are far more important questions between the U.S. and Japan. The key to the dolphin business is getting Japanese to oppose it. But will this help? Or on the contrary, will it start a nationalistic reaction against meddling by a (foreign) country,” said Dujarric.

Kennedy’s appointment in November was widely hailed in Japan as a sign of the special relationship between the two countries. Kennedy is the daughter of former president John F. Kennedy and a longtime supporter of President Obama; thousands turned out when she arrived at the Imperial Palace in a horse-drawn carriage to present her credentials to the emperor.

Kennedy has remained largely popular, visiting the region devastated by the 2011 earthquake and tsunami, and regularly tweeting news and photos from family trips around the country. Her Twitter account has more than 70,000 followers.

Critics of Kennedy’s appointment pointed to her lack of government experience and Japan’s crucial role in the U.S. “rebalance” to Asia. Japan is embroiled in tense disputes with neighboring China and South Korea over territorial claims and historical issues, and conservative Prime Minister Shinzo Abe is pushing for major changes to Japan’s pacifist constitution.

But Kennedy seemed to show resolve last month when the U.S. Embassy issued an unusually strong official statement expressing “disappointment” over Abe’s visit to the war-linked Yasukuni Shrine.

That’s all good, says Nancy Snow, a visiting professor of mass communications at Keio University, in Tokyo.

“I salute her for generating discussion on this issue,” Snow said in an e-mail Tuesday. “CK doesn’t have to agree with every Japanese position. She’s there to represent the U.S. position.”