Japanese Foreign Minister Yoshimasa Hayashi and his U.S. counterpart Antony Blinken on Friday shared "grave concern" over the Russian military buildup near Ukraine's border, with drills by Moscow fueling fears of a possible invasion, according to Japanese officials.

During their talks in Australia, Hayashi and Blinken also agreed to oppose any unilateral attempts to change the status quo in the East and South China seas, the officials said, as the two nations seek to bolster their security alliance to counter China's growing military and economic clout in the Indo-Pacific region.

Their second in-person meeting since Hayashi assumed his post in November was held on the sidelines of a gathering of foreign ministers of the Quad group, including Australia and India, in the Australian city of Melbourne the same day.

Japanese Foreign Minister Yoshimasa Hayashi (R) and his U.S. counterpart Antony Blinken are pictured in Melbourne on Feb. 11, 2022. (Kyodo)

Blinken said at the outset of the talks that he wanted to "check signals on the multiplicity of challenges the United States and Japan are facing together" through the bilateral meeting, according to the U.S. State Department.

The bilateral talks came after Russia launched military exercises in Belarus on Thursday, heightening tensions over a build-up of its troops along its border with Ukraine.

U.S President Joe Biden said in an interview aired Thursday with U.S. television network NBC that Americans who remain in Ukraine "should leave now," while Jens Stoltenberg, secretary general of the North Atlantic Treaty Organization, said that now is "the most dangerous moment" for Europe's security.

The Japanese and U.S. ministers reaffirmed their efforts to support Ukraine's sovereignty and territorial integrity, according to the Japanese Foreign Ministry.

Japan, a major liquefied natural gas purchaser, decided on Wednesday to provide a portion of its LNG imports to Europe from March at the request of the Western nations.

Washington and its NATO allies have indicated that they would impose economic and financial sanctions on Russia if it uses military force against Ukraine. Moscow, in retaliation, could cut off natural gas supplies to Europe, which relies on Russia for 40 percent of its imports.

Prime Minister Fumio Kishida said Japan would take "strong action in response to any attack" on Ukraine when he held a virtual summit with U.S President Joe Biden late last month. Washington has urged Japan to consider imposing economic sanctions if Russia launches an invasion, according to diplomatic sources.

Hayashi and Blinken also vowed close cooperation to address the North Korean missile and nuclear threat, calling it a "serious concern" after Pyongyang's repeated launches of ballistic missiles this year, according to the Japanese officials.

The two confirmed it is essential to strengthen deterrence and response capabilities of the Japan-U.S. alliance to ensure regional security, the Japanese ministry said.

Hayashi and Blinken also touched on a high-level bilateral economic dialogue during their talks after their leaders agreed during the online summit to launch the new initiative, an economic version of the "two-plus-two" security talks involving foreign and defense chiefs, the Japanese officials said.

The top diplomats of the two countries last met in December in Liverpool, England, on the sidelines of the two-day Group of Seven foreign ministers meeting.

After meeting with Blinken, Hayashi held his first face-to-face talks with his Indian counterpart Subrahmanyam Jaishankar ahead of the Quad gathering. Hayashi and Jaishankar pledged to realize Kishida's first visit to India as prime minister "at an appropriate time that is convenient for both," according to the ministry.