The foreign and defense ministers from Japan and Russia failed to find common ground on Thursday over disputes regarding Moscow's military buildup on a group of contested islands and Tokyo's planned deployment of a U.S.-developed missile defense system.

The so-called two-plus-two meeting was held for the fourth time since 2013 as part of efforts to enhance communication and build trust between the two countries, which have yet to sign a post-World War II peace treaty due to their long-standing territorial spat.

The ministries of the two countries, however, remained at odds over key security issues, other than that they agreed to work together toward the denuclearization of North Korea.

"We explained Japan's position that Russia's missile exercises and deployment of fighter jets to the Northern Territories is unacceptable," Japanese Foreign Minister Taro Kono said at a press conference in Tokyo after the talks, touching on the disputed islands off Hokkaido which are called the Southern Kurils in Russia.

Russian Foreign Minister Sergey Lavrov, who also attended the press conference, countered that the islands belong to Russia under international law, and that it has every right to conduct military activities there.

Moscow has deployed state-of-the-art Sukhoi Su-35 fighter jets and missiles on the islands. The Russian Defense Ministry's official newspaper has also recently reported that a firing exercise had been conducted on one of the islands, Etorofu, last fall using a new surface-to-air missile, ruffling feathers in Tokyo.

During the talks, Lavrov said he voiced apprehension regarding Japan's plan to deploy the land-based Aegis Ashore missile defense system made by the United States, calling it a move by Japan to allow Washington to use its territory as a base for its missile shield.

Implicitly criticizing the Japan-U.S. security alliance, he also said the Indo-Pacific region "needs a new security architecture."

Japanese Defense Minister Takeshi Iwaya told the press conference he assured the Russians that the missile defense system was purely intended to shore up Japan's defense capabilities and will not pose a threat to Russia's national security.

The foreign and defense ministers said they also exchanged views on North Korea's firing of short-range ballistic missiles into the sea earlier this month, and agreed to work together toward the denuclearization of the Korean Peninsula.

"We affirmed that North Korea's denuclearization is a common goal of our countries," Kono said.

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At a separate meeting earlier in the day between the defense ministers, Iwaya explained that Japan considers the ballistic missiles, which analysts say resemble the Russian Iskander, a clear violation of U.N. Security Council resolutions.

Russian Defense Minister Sergei Shoigu neither affirmed nor contested the view, according to Iwaya.

At the press conference, Shoigu said the two countries agreed to enhance cooperation between his country's navy and Japan's Maritime Self-Defense Force and will continue their joint search-and-rescue exercises.

The two-plus-two talks -- the first since last July -- took place about a month ahead of a planned meeting between Japanese Prime Minister Shinzo Abe and Russian President Vladimir Putin on the sidelines of the Group of 20 summit in Osaka, western Japan.

Abe is hoping to make progress in resolving the territorial dispute, ahead of a House of Councillors election in the summer.

Tokyo has argued the islands were illegally seized by the Soviet Union after Japan's 1945 surrender brought an end to World War II, while Moscow maintains it acquired them as part of the outcome of the war.

The following is the gist of the outcome of "two-plus-two" security talks between the foreign and defense ministers of Japan and Russia and a one-on-one meeting by the defense ministers held Thursday in Tokyo.

Japan:

-- says Russia's military activities on disputed islands off Hokkaido are unacceptable, calls for calm attitude.

-- says its planned deployment of Aegis Ashore missile defense system is for defense purposes and will not pose a threat to Russia.

-- says North Korea's recent firing of short-range ballistic missiles clearly violates U.N. Security Council resolutions.

Russia:

-- voices concerns over the deployment of the Aegis Ashore system.

-- asserts its military actions on disputed islands are legitimate.

-- calls for new security architecture in the Indo-Pacific region.

Japan, Russia:

-- confirm North Korea's denuclearization is common goal and agree to cooperate to realize it.