North Korean leader Kim Jong Un joined his troops in training to operate newly developed battle tanks as he called for bigger efforts to prepare for war, state media reported on March 14.
The North's tank training was seen as a response to the annual 11-day South Korean-U.S. military drills.
The North views its rivals' exercises as a rehearsal for invasion.
The North's training on March 13 was designed to inspect tankmen's combat capabilities and involved the new-type main battle tank that Kim called "the world's most powerful," the official Korean Central News Agency said.
During the training, heavy tanks moved around various simulated harsh combat circumstances and fired rounds at targets.
Kim mounted one of the new-type tanks and drove it himself, "adding to the high militant spirit of the tankmen of our army," KCNA said.
North Korea's Defense Ministry earlier vowed to carry out "responsible military activities" in reaction to the ongoing South Korea-US military exercises in the South.
Kim later supervised artillery firing drills.
The South Korean-US training involve a computer-simulated command post training and 48 kinds of field exercises, twice the number conducted last year.
North Korea has dialed up its weapons testing activities since early 2022 in a bid to modernise and enlarge its nuclear and missile arsenals.
The US and South Korea have expanded their training exercises and a trilateral drill involving Japan in response.
Experts say Kim likely wants to use his upgraded weapons arsenal to win US concessions like extensive relief of international sanctions on North Korea.
They say North Korea is expected to extend its testing activities and ramp up warlike rhetoric this year as both the United States and South Korea hold major elections.
North Korea's Defense Ministry earlier vowed to carry out "responsible military activities" in reaction to the ongoing South Korea-US military exercises in the South. Kim later supervised artillery firing drills.
Pyongyang's official Korean Central News Agency said Kim urged his troops to be prepared to "overwhelmingly respond to and contain" the military action of the North's enemies, which he said were proceeding with "all sorts of more frantic war preparation moves".
He said frontline units should sharpen their capabilities to carry out their two main "strategic missions, that is, first to deter war and second to take the initiative in war".
South Korea's Unification Ministry later urged North Korea to stop raising tensions with "reckless nuclear and missile programs and military provocations".
Vice spokesperson Lee Hyo-jung told reporters that North Korea must focus instead on caring for people's livelihoods and take a path toward building peace on the Korean Peninsula.
The KCNA report did not specify what types of weapons were involved in Thursday's exercise or how many rockets were fired.
Some of the North's newer short-range weapons targeting South Korea includes large-sized multiple rocket launchers that experts say blur the boundaries between artillery and ballistic missile systems.
North Korea describes some of its more advanced short-range systems as tactical weapons, which implies an intent to arm them with lower-yield battlefield nuclear weapons.
Experts say the North with the wording is communicating a threat to proactively use those weapons during conventional warfare to blunt the stronger conventional forces of South Korea and the United States, which keeps about 28,000 troops in South Korea to help deter potential aggression from North Korea.
Kim's comments were in line with an escalatory nuclear doctrine the North set into law last year, which authorises preemptive nuclear strikes in situations where it may perceive its leadership as under threat, including conventional clashes.
Kim watched the firings from an observation post along with military officials and his daughter, believed to be named Kim Ju-ae and around 10 years old.
She has appeared at several events tied to his military since first being showcased at an ICBM test launch in November, and analysts believe the events and elevated descriptions of her in state media are meant to show the world he has no intention to voluntarily surrender his nuclear weapons, which he apparently sees as the strongest guarantee of his survival and the extension of his family's dynastic rule.
Coming off a record year in missile testing, North Korea has conducted additional weapons demonstrations in 2023.
Experts say North Korea with its heightened testing activity and threats is trying to claim a dual ability to conduct nuclear strikes against South Korea and the US mainland.
Kim's campaign is aimed at forcing the United States into accepting the North as a nuclear power and negotiating badly needed economic concessions from a position of strength, analysts say.
Diplomacy between the US and North Korea has stalled since 2019.
The South Korean and US militaries will conduct computer-simulated command post training March 13-23 and will resume their largest springtime field exercises, which were last held in 2018.
The allies' regular drills were cancelled or scaled back to support diplomacy or because of the COVID-19 pandemic but they renewed them after the diplomacy collapsed and North Korea's threats and weapons testing escalated.
On Tuesday, Kim Yo-jong, the North Korean leader's powerful sister and one of Pyongyang's top foreign policy officials, warned that her country is ready if necessary to take "quick, overwhelming action" in the face of the allies' expanded drills.
In previous statements, she threatened to turn the Pacific into North Korea's firing range and repeatedly implied that the North might test-fire an ICBM toward those waters on a standard ballistic trajectory, which would be seen as one of its most provocative weapons demonstrations yet.
All of North Korea's ICBM tests since 2017 have been conducted on a high angle to avoid the territories of neighbours.