Moscow test-fired anti-ship missiles in the Sea of Japan, Russia’s Defense Ministry said on Tuesday, with two boats launching a simulated missile attack on a mock enemy warship about 100 kilometers (60 miles) away.

According to the ministry, the target was struck by two Moskit cruise missiles.

The Moskit, whose North Atlantic Treaty Organization reporting name is the SS-N-22 Sunburn, is a supersonic anti-ship cruise missile that has conventional and nuclear warhead capacity. The Soviet-built cruise missile is capable of flying at a speed three times the speed of sound and has a range of up to 250 km (155 mi).

The ministry said the exercise, which included other warships and naval aircraft, took place in the Peter the Great Gulf in the Sea of Japan, but did not give more precise coordinates. The gulf borders the Russian Pacific Fleet headquarters at Fokino and is about 700 km (430 mi) from Japan’s northern island of Hokkaido.

The Russian military has conducted regular drills across the country, and Russian warships have continued maneuvers as the fighting in Ukraine is now in its second year — exercises that were intended to train the troops and showcase the country’s military capability.

The United States Navy’s 7th Fleet did not immediately respond to requests for comment.

Japan reacted calmly to the missile exercise, which was conducted near the eastern city of Vladivostok, rather than directly into the waters between the two countries.

Japanese Deputy Chief Cabinet Secretary Yoshihiko Isozaki told a news conference later on Tuesday that Tokyo would continue to monitor Russia’s military operations, as it has been stepping up activity in the region.

Japan does not plan to lodge a protest to Russia over the missile exercise, said Tasuku Matsuki, the Japanese Foreign Ministry official in charge of Russia, noting that its location — Peter the Great Bay — is considered a Russian coast, though it is facing the water between the two countries.

“On the whole, Japan is concerned about Russia’s increasing military activities around the Japanese coasts and watching them with great interest,” he said.

He added that Russia had conducted missile drills in that area in the past and issued maritime advisories ahead of time.

Russian nuclear-capable Tu-95 bombers flew over the Sea of Japan for several hours last week.

Last September, Japan protested multinational military exercises on the Russian-held Kuril Islands — some of which are claimed by Tokyo — and expressed concern about Russian and Chinese warships conducting shooting drills in the Sea of Japan.

Russia also tested submarinelaunched missiles in the Sea of Japan last year.