The South Korean, U.S. and Japanese navies began their first anti-submarine drills in six months on Monday to boost their coordination against increasing North Korean missile threats, South Korea’s military said. The two-day drills come as North Korea’s recent unveiling of a type of battlefield nuclear warhead prompted worries the country may conduct first nuclear test since 2017. The maritime exercises in international waters off South Korea’s southern island of Jeju involved the nuclear-powered USS Nimitz aircraft carrier and naval destroyers from South Korea, the U.S. and Japan, South Korea’s Defense Ministry said in a statement. Also Read: Kim wants N. Korea to make more nuclear material for bombs The training was arranged to improve the three countries’ capacities to respond to underwater security threats posed by North Korea’s advancing submarine-launched ballistic missiles and other assets, the statement said. It said the three countries were to detect and track unmanned South Korean and U.S. underwater vehicles posing as enemy submarines and other assets. Submarine-launched missiles by North Korea are serious security threats to the United States and its allies because it’s harder to spot such launches in advance. In recent year, the North has been testing sophisticated underwater-launched ballistic missiles and pushing to build bigger submarines including a nuclear-powered one. Last month, North Korea performed a barrage of missile tests in response to the earlier South Korea-U.S. bilateral military drills. The weapons tested included a nuclear-capable underwater drone and a submarine-launched cruise missile, which suggest North Korea is trying to diversify its kinds of underwater weapons. Also Read: North Korea test-fires 2 more missiles as US sends carrier Photographs in North Korea's state media last week showed about 10 capsule-shaped, red-tipped warheads called “Hwasan (volcano)-31” with different serial numbers. A poster on a nearby wall listed eight kinds of short-range weapons that can carry the “Hwasan-31” warhead. The previous test flights of those weapons show they are capable of striking key targets in South Korea, including U.S. military bases there. Some observers say the warhead’s unveiling may be a prelude to a nuclear test as North Korea's last two tests in 2016 and 2017 followed the disclosures of other warheads. If it does conduct a nuclear test, it would be its seventh detonation overall and the first since September 2017. Foreign experts debate whether North Korea has functioning nuclear-armed missiles. But South Korea’s defense minister, Lee Jong-Sup, recently said the North’s technology to build miniaturized warheads to be mounted on advanced short-range missiles was believed to have made considerable progress. North Korea could carry out new missile tests in response to the South Korea-U.S.-Japan drills because it views such training as a security threat. North Korean leader Kim Jong Un called recent South Korea-U.S. exercises “reckless military provocations” that disregarded North Korea's "patience and warning.” In remarks carried in the Defense Ministry statement, Rear Adm. Kim Inho, chief of the South Korean forces involved in the trilateral drills, said “We’ll decisively respond to and neutralize any type of provocation by North Korea.” In addition to anti-submarine drills, the three countries will practice humanitarian search-and-rescue operations, including saving people who fall into the water and treating emergency patients. It would be the three countries’ first such training in seven years, the Defense Ministry statement said.

India's brand-new home-made submarine headed out for its first sea trial on Tuesday, a year ahead of its induction into the country's naval fleet as INS Vagir. The U-boat -- the fifth of the six Scorpene-class submarines -- was built by the state-owned Mazagon Dock Shipbuilders Limited (MDL) with help from France's Naval Group. "Despite the pandemic, MDL delivered two submarines of the Project 75 last year. The sea trials of the fifth submarine are a significant milestone," the Indian Navy said in a statement. Read: How India plans to spiff up economic growth Four submarines of this French-designed class are already in Indian naval service. The Scorpene-class submarines have superior stealth features and are also equipped with both long-range guided torpedoes as well as anti-ship missiles.  These submarines can launch anti-surface and anti-submarine warfare due to their low-radiated noise levels and ability to launch crippling attacks with precision-guided weapons.

Indonesia’s military on Sunday officially said all 53 crew members from a submarine that sank and broke apart last week are dead, and that search teams had located the vessel’s wreckage on the ocean floor. The grim announcement comes a day after Indonesia said the submarine was considered sunk, not merely missing, but did not explicitly say whether the crew was dead. Officials had also said the KRI Nanggala 402′s oxygen supply would have run out early Saturday, three days after the vessel went missing off the resort island of Bali. “We received underwater pictures that are confirmed as the parts of the submarine, including its rear vertical rudder, anchors, outer pressure body, embossed dive rudder and other ship parts,” military chief Hadi Tjahjanto told reporters in Bali on Sunday. “With this authentic evidence, we can declare that KRI Nanggala 402 has sunk and all the crew members are dead,” Tjahjanto said. Also read: Indonesia navy declares lost sub with 53 aboard sunk An underwater robot equipped with cameras found the lost submarine lying in at least three pieces on the ocean floor at a depth of 838 meters (2,750 feet), said Adm. Yudo Margono, the navy’s chief of staff. That’s much deeper than the KRI Nanggala 402′s collapse depth of 200 meters (655 feet), at which point water pressure would be greater than the hull could withstand, according to earlier navy statements. Margono said emergency survival suits that are normally kept in boxes were found floating underwater, apparently indicated the crew may have tried to put them on during the emergency. The cause of the submarine’s sinking remains uncertain. The navy had previously said an electrical failure could have left the submarine unable to execute emergency procedures to resurface. Also read: Indonesia navy finds items from lost sub, indicating it sunk The wreckage is located 1,500 meters (yards) to the south of the site where the submarine last dove Wednesday, off Bali’s northern coast, Margono said. Photos of the debris were presented at the press conference. The underwater robot deployed by Singaporean vessel MV Swift Rescue provided the images, while the Indonesian vessel KRI Rigel had scanned the area where the submarine was believed to have sunk using multibeam sonar and a magnetometer, Tjahjanto said. Indonesia’s President Joko Widodo delivered his condolences in a televised address Sunday. “All Indonesians convey deep sorrow for this tragedy, especially to all of the families of the submarine’s crew. They are the best sons of the nation, patriots guarding the sovereignty of the country,” Widodo said. Also read: US plane joins hunt for Indonesian sub after air runs out An American reconnaissance plane, a P-8 Poseidon, landed Saturday and had been set to join the search, along with 20 Indonesian ships, a sonar-equipped Australian warship and four Indonesian aircraft. The German-built diesel-powered KRI Nanggala 402 had been in service in Indonesia since 1981 and was carrying 49 crew members and three gunners as well as its commander, the Indonesian Defense Ministry said. Indonesia, the world’s largest archipelago nation with more than 17,000 islands, has faced growing challenges to its maritime claims in recent years, including numerous incidents involving Chinese vessels near the Natuna islands.

Indonesia’s navy on Saturday declared its missing submarine had sunk and cracked open after finding items from the vessel over the past two days, apparently ending hope of finding any of the 53 crew members alive. Military chief Hadi Tjahjanto said the presence of an oil slick as well as debris near the site where the submarine last dove Wednesday off the island of Bali were clear proof the KRI Nanggala 402 had sunk. Indonesian officials earlier considered the vessel to be only missing, but said the submarine’s oxygen supply would have run out early Saturday. Navy Chief Yudo Margono told a press conference in Bali, “If it’s an explosion, it will be in pieces. The cracks happened gradually in some parts when it went down from 300 meters to 400 meters to 500 meters. ... If there was an explosion, it would be heard by the sonar.” The navy previously said it believes the submarine sank to a depth of 600-700 meters (2,000-2,300 feet), much deeper than its collapse depth of 200 meters (655 feet), at which point water pressure would be greater than the hull could withstand. “With the authentic evidence we found believed to be from the submarine, we have now moved from the ‘sub miss’ phase to ‘sub sunk,’” Margono said at the press conference, in which the found items were displayed. ADVERTISEMENT   The cause of the disappearance was still uncertain. The navy had previously said an electrical failure could have left the submarine unable to execute emergency procedures to resurface. Margono said that in the past two days, searchers found parts of a torpedo straightener, a grease bottle believed to be used to oil the periscope, debris from prayer rugs and a broken piece from a coolant pipe that was refitted on the submarine in South Korea in 2012. Margono said rescue teams from Indonesia and other countries will evaluate the findings. He said no bodies have been found so far. An American reconnaissance plane, a P-8 Poseidon, landed early Saturday and had been set to join the search, along with 20 Indonesian ships, a sonar-equipped Australian warship and four Indonesian aircraft. Singaporean rescue ships were also expected Saturday, while Malaysian rescue vessels were due to arrive Sunday, bolstering the underwater hunt, officials said earlier Saturday. Family members had held out hopes for survivors but there were no sign of life from the vessel. Indonesian President Joko Widodo had ordered all-out efforts to locate the submarine and asked Indonesians to pray for the crew’s safe return. The German-built diesel-powered KRI Nanggala 402 had been in service in Indonesia since 1981 and was carrying 49 crew members and three gunners as well as its commander, the Indonesian Defense Ministry said. Indonesia, the world’s largest archipelago nation with more than 17,000 islands, has faced growing challenges to its maritime claims in recent years, including numerous incidents involving Chinese vessels near the Natuna islands.

Indonesian navy ships were scouring the waters off Bali on Friday as they raced against time to find a submarine that disappeared two days ago and has less than a day’s supply of oxygen left for its 53 crew. The KRI Nanggala 402 went missing after its last reported dive Wednesday off the resort island, and concern is mounting the submarine may have sunk too deep to reach or recover. The navy chief said the submarine was expected to run out of oxygen by around 3 a.m. Saturday. “We will maximize the effort today, until the time limit tomorrow 3 a.m.,” military spokesperson Maj. Gen. Achmad Riad told reporters. There have been no signs of life from the submarine, but the spokesperson refused to speculate on its fate. A total of 24 navy and other ships and a patrol plane were being mobilized for Friday’s search with a focus on the area where an oil slick was found after the submarine disappeared during an exercise. Rescuers made similar massive searches in the past two days. An Australian warship equipped with a sonar device and a helicopter was set to arrive later Friday. A second Australian warship as well as Singaporean and Malaysian rescue ships were also expected in the coming days. “These two Australian ships will help expand the search area and extend the duration of search effort,” Australian Navy Rear Adm. Mark Hammond said. On Friday, Indonesian President Joko Widodo was heading to Banyuwangi port, where the rescue ships left earlier. He asked Indonesians to pray for the crew’s safe return, while ordering all-out efforts to locate the stricken submarine. “Our main priority is the safety of 53 crew members,” Widodo said in a televised address on Thursday. “To the family of the crew members, I can understand your feelings and we are doing our best to save all crew members on board.” There’s been no conclusive evidence the oil slick was from the sub. Navy Chief of Staff Adm. Yudo Margono said oil could have spilled from a crack in the submarine’s fuel tank or the crew could have released fuel and fluids to reduce the vessel’s weight so it could surface. Margono said an unidentified object with high magnetism was located at a depth of 50 to 100 meters (165 to 330 feet) and officials held out hope it’s the submarine. The navy also said it believes the submarine sank to a depth of 600-700 meters (2,000-2,300 feet), much deeper than its collapse depth at which water pressure would be greater than the hull could withstand. The vessel’s collapse depth was estimated at 200 meters (655 feet) by a South Korean company that refitted the vessel in 2009-2012. The cause of the disappearance is still uncertain. The navy has said an electrical failure could have left the submarine unable to execute emergency procedures to resurface. Pentagon press secretary John Kirby said the United States is sending airborne assets to assist in the search. “We are deeply saddened by the news of Indonesia’s lost submarine, and our thoughts are with the Indonesian sailors and their families,” Kirby said. Other countries have also offered assistance. Submarine accidents are often disastrous. In 2000, the Russian nuclear submarine Kursk suffered internal explosions and sank during maneuvers in the Barents Sea. Most of its 118 crew died instantly, but 23 men fled to a rear compartment before they later died, mainly of suffocation. In November 2017, an Argentine submarine went missing with 44 crew members in the South Atlantic, almost a year before its wreckage was found at a depth of 800 meters (2,625 feet). But in 2005, seven men aboard a Russian mini-sub were rescued nearly three days after their vessel became snagged by fishing nets and cables in the Pacific Ocean. They had only six hours of oxygen left before reaching the surface. The German-built diesel-powered KRI Nanggala 402 has been in service in Indonesia since 1981 and was carrying 49 crew members and three gunners as well as its commander, the Indonesian Defense Ministry said. Indonesia, the world’s largest archipelago nation with more than 17,000 islands, has faced growing challenges to its maritime claims in recent years, including numerous incidents involving Chinese vessels near the Natuna islands.