U.S President Donald Trump and President Moon of the Republic of Korea walk the colonnade before giving a joint statements in the Rose Garden of the White House in Washington, DC, on June 30, 2017.

The United States will send "strategic" military assets to South Korea on a more regular basis to better deter North Korea, the South's national security adviser said Thursday.

The decision comes at a time of escalating tensions between the United States and North Korea, with many analysts concerned that incendiary rhetoric, combined with more frequent flyovers by American bombers, could lead to a catastrophic miscalculation.

Chung Eui-young, national security adviser to President Moon Jae-in, told lawmakers in Seoul that American "strategic assets" could be deployed to South Korea on a "rotational" basis before the end of the year.

"This will help us expand our defense capabilities," he told the lawmakers, according to Park Wan-joo, spokesman of the ruling Democratic Party.

He did not define "strategic assets," but South Korean officials usually use the term to refer to B-52 bombers, stealth warplanes, nuclear-powered submarines and aircraft carriers.

The Pentagon confirmed that Moon and President Trump agreed to "enhanced deployment of U.S. strategic assets in and around South Korea on a rotational basis" when they met on the sidelines of the United Nations General Assembly last week.

"We continue to work with our ROK allies on the best way forward to meet this intent but it would be inappropriate to discuss any additional details at this time," said Christopher Logan, a Pentagon spokesman.

South Korean lawmakers were told that Washington had put its pledge on the deployment in writing, Park confirmed.

North Korea's foreign minister recently warned that his country's military was ready to shoot down American military planes even if they were not in North Korean airspace.

To celebrate its Armed Forces Day, which falls on Sunday, South Korea's military showed off some of its new weapons during a parade Thursday. For the first time, the military displayed its Hyunmoo ballistic missiles, which can reach all of North Korea and are a key element of its "Kill Chain" preemptive-strike system.

"Our government's determination to protect peace requires strong defense capabilities, and we will stand up against reckless provocations with strong punishment," Moon said after inspecting the weapons.

"Securing counter capabilities against North Korean nuclear and missile threats is the most urgent task. We must further strengthen our Kill Chain and Korean missile defense system," the president said.

South Korean Defense Minister Song Young-moo last month asked his American counterpart, Jim Mattis, to send such military hardware to the southern half of the peninsula on a regular basis.

A poll that YTN, a South Korean cable news channel, commissioned in August found that 68 percent of respondents said they supported bringing tactical nuclear weapons back to South Korea.

This issue has become more and more important to South Korea as tensions with North Korea have risen. With top Trump administration officials repeatedly saying that military options for dealing with Kim Jong Un's regime are on the table, some in South Korea have grown increasingly concerned about becoming collateral damage.

The Pentagon is typically resistant to talking about the deployment of nuclear weapons anywhere, citing security concerns. It also does not often talk about the deployment of submarines, whose benefits as part of the so-called "Silent Service" include lurking undetected beneath the ocean's surface.

Mattis did disclose recently that he spoke with Song about potentially deploying tactical nuclear weapons after Song brought up the idea during a visit to Washington, but the Pentagon chief has declined to elaborate.

"I won't talk about where we keep nuclear weapons, where we station them or anything like that," he said, speaking to reporters Sept. 13. "It's simply a longstanding policy so . . . our adversaries never know where they're at. It's part of the deterrent that they cannot target them all. There's always a great big question mark."

The Pentagon has kept bombers in the Pacific for years at Guam's Andersen Air Force Base, perhaps one of the main reasons that the North Korean regime has threatened to strike the U.S. island territory. The United States has flown numerous flights over the Korean Peninsula recently, and North Korea has threatened to shoot them down, even if they are international airspace where they are legally allowed.

U.S. bombers include the B-1B Lancer, the B-2 Spirit and the B-52 Stratofortress. In Guam, the Air Force has primarily maintained B-1Bs, which once were able to carry nuclear bombs but have not been able to do so since 2007, when the service began removing hardware for them to carry nuclear weapons as part of the New START Treaty with Russia.

North Korea has enough conventional artillery trained on the greater Seoul area, home to 25 million people as well as several large U.S. military bases, to cause widespread devastation before the American and South Korean militaries can respond.

If North Korea were to start unleashing its artillery on the South, it would be able to fire about 4,000 rounds an hour, Roger Cavazos of the Nautilus Institute estimated in a 2012 study. There would be 2,811 fatalities in the initial volley and 64,000 people could be killed that first day, the majority of them in the first three hours, he wrote.

As North Korea has continued to show off its growing arsenal - detonating a hydrogen bomb and firing increasingly long-range missiles - the U.S. and South Korean militaries have been conducting drills as a "show of strength."

Air Force B-1B bombers from Guam and Marine Corps F-35B fighters from Iwakuni, Japan, have been dropping bombs on a training range in South Korea, just a few dozen miles from the border with the North.

South Korean F-15K fighters have been doing the same, and South Korea has tested missiles designed to show that North Korea's nuclear and missile test sites are within range.

But South Korean officials have been pushing for more than just flyovers from warplanes based in Japan or Guam: They want them to land in South Korea to show greater commitment to the military alliance.

But there are logistical reasons that cannot happen, Jon Wolfsthal, a nuclear expert who served on President Barack Obama's National Security Council, has said. Military airstrips in South Korea are not long enough for big, heavy B-52s, and the United States does not want its high-tech fighter jets sitting within North Korean artillery range, he said.

The United States regularly sends aircraft carriers, as well as Los Angeles-class submarines, to South Korea during annual joint military exercises. But the South Koreans are seeking a more consistent and higher-power show of American military commitment.