Japan began exercises Monday with the U.S. Army in Hokkaido, a day after it started naval maneuvers with Russia 800 km away off the coast of Vladivostok.

The drills illustrate the balance Prime Minister Shinzo Abe must strike between his attempts to mend relations with Russia and the need to bolster his country’s alliance with the United States as a backstop to a more assertive China in the region.

While Russia supplies about 10 percent of Japan’s natural gas needs, and potentially more, Japan has backed Group of Seven sanctions over Russia’s infiltration of Ukraine. That sparked recriminations from Russia and raised military tensions, with Japanese jets scrambling hundreds of times to head off approaches by Russian aircraft in the three months through June.

“What’s difficult for Japan is that the alliance with the U.S. is the centerpiece of its security policy,” said Taisuke Abiru, a research fellow specializing in Russia at The Tokyo Foundation, a research group. “How can they maintain this alongside relations with Russia? This is an extremely important problem for Prime Minister Abe now.”

Abe had sought to strengthen ties with Russia until that country’s annexation of Crimea in March. He may use his first summit with President Vladimir Putin in nine months at November’s meeting of the Asia-Pacific Economic Cooperation forum in Beijing to restart his diplomatic push.

The roar of F-15 fighter jets is almost constant at Japan’s most northerly air base in Chitose, Hokkaido, even though the number of approaches by Russian planes has fallen.

Air Self-Defense Force aircraft were scrambled 89 times to head off Russian planes in the quarter that ended in September, compared with 235 in April-June, the Defense Ministry said this month.

The Russian missions are probably a message aimed at the U.S., which has 38,000 military personnel in Japan, Abiru said.

The 12-day Operation Orient Shield, the U.S. Army’s first maneuvering drill with the Ground Self-Defense Force in Hokkaido in four years, involves about 2,000 military personnel. The U.S. sent Apache helicopters and Stryker combat vehicles.

Japan has separately dispatched the destroyer Hamagiri to Vladivostok for the first joint exercise since Russia’s takeover of Crimea. Even though U.S. and Russian naval ties are frozen, Vice Adm. Robert Thomas, commander of the U.S. Navy’s 7th Fleet, sees Japan’s exercises with Russia as a useful point of contact.

The Maritime Self-Defense Force acts as “an interlocutor while the 7th Fleet is on hold interacting with the Russian Federation Navy,” Thomas told reporters in Tokyo last week.

The row over ownership of the small Russian-held group of islands off Hokkaido has lingered since the Soviet Union ended a neutrality pact with Japan days before the end of World War II, invading the islands and expelling thousands of Japanese residents.

Pledging to resolve the dispute over the islands, Abe has held five summits with Putin since taking office in December 2012.

Even though a planned visit to Tokyo by Putin this autumn has been postponed, the two leaders have kept the lines of communication open. They called one another on their respective birthdays in September and October, and met briefly on the sidelines of a forum in Milan this month.

The Japanese government and corporations are continuing to consider importing more gas from Russia’s Sakhalin Island, which could increase the share of Japan’s gas needs supplied by Russia to about 17 to 18 percent, Abiru said.

Putin is interested in continuing what was a regular and steady dialogue with Abe, said Sheila Smith, a senior fellow for Japan studies at the Council on Foreign Relations in Washington.

“Of course the state visit cannot happen given the annexation of Crimea and Russian military intervention in Ukraine,” she said. “Nonetheless, there is ample reason for Japan to pursue its own interests with Russia.”