ISTANBUL

Japan Monday expressed concerns about what it called an “increasingly severe” security situation surrounding the country.

Japanese Defense Minister Nobuo Kishi told the visiting US Secretary of the Navy Carlos Del Toro on Monday about the encirclement of Japan by at least 10 Russian and Chinese ships in the past few days.

In a statement, the Japanese Defense Ministry said five Russian Navy ships sailed through the Sea of Japan after they sailed around the country’s shores, Tokyo-based Kyodo News reported.

The same Russian ships had previously “formed a flotilla” with five Chinese ships that had sailed around most of the Japanese archipelago, the ministry added. The two navies parted ways on Saturday.

“The security situation surrounding Japan is becoming increasingly severe,” Kishi told Toro.

During the meeting, the minister also took up North Korea's recent test-firing of a submarine-launched ballistic missile.

The ships entered the sea through the Tsushima Strait in Japan’s southwest.

“The 10 Russian and Chinese ships are believed to include vessels that took part in a joint drill conducted by the two countries in the Sea of Japan in mid-October,” the ministry said.

On Sunday morning, a helicopter was also seen taking off and landing on a frigate, one of the five Russian ships, some 60 kilometers (37 miles) northeast of Tsushima, the report added.

“The US wishes to strengthen cooperation with Japan in the maritime domain,” Toro was quoted as having said.

Japan and the United States are long-time security allies.

Yoshihiko Isozaki, Japan's deputy chief cabinet secretary, told a news conference Monday that Prime Minister Kishida Fumio’s government saw the developments with “high interest.”

“We will continue to conduct surveillance activities thoroughly in the waters and airspace surrounding Japan,” Isozaki said.