Vietnam on Monday received the second of two Russian-made guided missile frigates, local media reported, boosting its naval firepower amid maritime tensions with China.

The Gepard class frigate — which an analyst called Vietnam’s most modern warship — arrived at Cam Ranh port on the country’s south-central coast, reports said.

The first frigate reached Vietnam in March, state-controlled Tuoi Tre newspaper said.

“It alters the naval game,” said Carl Thayer, a veteran Australia-based analyst of Vietnam. “A boat of that kind provides muscle for Vietnam.”

The frigates were ordered several years ago as part of a naval upgrade by Hanoi, which is also buying six Russian submarines and foreign-built maritime patrol aircraft.

Beijing and Hanoi have a long-standing territorial dispute over the Paracel and Spratly archipelagos, which are potentially rich in oil and gas deposits and straddle vital commercial shipping lanes.

Relations reached their lowest point in years when Vietnam in May accused Chinese marine surveillance vessels of cutting the exploration cables of an oil survey ship inside the country’s exclusive economic zone.

Vietnamese fishermen working in disputed waters have reported numerous seizures of their catch and equipment in recent years.

Thayer said the new helicopter-capable frigates will back up the fishermen with a more powerful vessel than the lightly-armed civilian-run Chinese surveillance ships.

Other nations in the region have also accused China in recent months of becoming more aggressive in enforcing its claims to essentially all of the South China Sea.

The Philippines, Malaysia, Brunei and Taiwan have also staked claims to the Spratlys.