(CNN) US F-22 fighter jets roared into the sky over South Korea on Monday to start air combat exercises that North Korea says are pushing the peninsula to the brink of nuclear war.

A US 7th Air Force official said the top-of-the-line F-22s are being joined by Air Force and Marine Corps F-35s in the largest concentration of fifth-generation fighter jets ever in South Korea.

A senior South Korean Air Force official told CNN on Monday that the war games will include attacks against a mock North Korean missile launch site with mock North Korean radars.

Experts say the stealthy F-22s and F-35s would be key to any such actual attack as they are invisible to North Korean radars.

The fighter jets are among 230 US and South Korean aircraft -- supported by 12,000 troops -- participating in the annual Vigilant Ace 18 air combat drills, which are scheduled to end Friday.

North Korea state media said Monday that "ceaseless large-scale war games" by the US and South Korea are "creating a situation that a nuclear war may break out any moment."

Over the weekend, official sources from both North Korea and the US said the chances of war are growing.

A US Air Force F-16 and four F-35A fighter jets taxi toward the end of the runway during exercise Vigilant Ace at Kunsan Air Base in South Korea.

North Korea's Foreign Ministry said US President Donald Trump was "begging for a nuclear war" through what it called an "extremely dangerous nuclear gamble on the Korean Peninsula," in a statement released Saturday.

The same day, White House national security adviser HR McMaster told a conference in California that the chances for war on the Korean Peninsula grow daily.

"I think it's increasing every day, which means that we are in a race, really, we are in a race to be able to solve this problem," McMaster told an audience at the Reagan National Defense Forum in Simi Valley.

McMaster made the comment when asked if North Korea's launch of an intercontinental ballistic missile in the early hours of Wednesday morning local time had increased the chance of war.

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"There are ways to address this problem short of armed conflict, but it is a race because he's getting closer and closer, and there's not much time left," McMaster said, referring to North Korean leader Kim Jong Un.

With every missile launch or nuclear test, Kim has improved his country's capabilities, McMaster said.

US Sen. Lindsey Graham, a Republican hawk who sits on the Senate Armed Services Committee, told CBS News that North Korea's advancing military technology makes the possibility of pre-emptive war more likely.

"I think we're really running out of time," he said.

Graham also said he will urge the Pentagon not to send any military dependents to South Korea.

"It's crazy to send spouses and children to South Korea, given the provocation of North Korea. So I want them to stop sending dependents. And I think it's now time to start moving American dependents out of South Korea," he said.

Air combat exercise begins

Six US Air Force F-22 Raptors, Washington's top-of-the-line stealth fighters, arrived in South Korea on Saturday to participate in the Vigilant Ace 18 air combat exercise, an annual US-South Korea drill the US Air Force says is designed to boost the "combat effectiveness" of the alliance.

Photos: In the U.S. Air Force fleet B-52 Stratofortress – The first versions of this long-range heavy bomber flew in 1954. A total of 744 were built, the last of those in 1962. The Air Force maintains 58 B-52s in the active force and 18 in the Reserve. A single B-52 can carry 70,000 pounds of mixed munitions, including bombs, missiles and mines. The eight-engine jets have a range of 8,800 miles. Hide Caption 1 of 24 Photos: In the U.S. Air Force fleet C-130 Hercules transport – A C-130J Super Hercules from the 37th Airlift Squadron flies over Normandy, France, June 3, 2015. First delivered to the Air Force in 1956, the C-130 remains one of the service's most important airlift platforms. More than 140 are still in active units, with more than 180 in the National Guard and a hundred more in the Reserve. The C-130 is powered by four turboprop engines. Hide Caption 2 of 24 Photos: In the U.S. Air Force fleet AC-130 gunships – The AC-130H Spectre and the AC-130U Spooky gunships are designed for close air support, air interdiction and force protection. Armaments on the Spectre include 40mm and 105mm cannons. The Spooky adds a 25mm Gatling gun. Hide Caption 3 of 24 Photos: In the U.S. Air Force fleet F-22 Raptor – The twin-engine F-22 stealth fighter, flown by a single pilot and armed with a 20mm cannon, heat-seeking missiles, radar-guided missiles and radar-guided bombs, can perform both air-to-air and air-to-ground missions. The service has 183 of the Raptors, which went operational in 2005. Hide Caption 4 of 24 Photos: In the U.S. Air Force fleet The single-engine F-35A is the Air Force's eventual replacement for the F-16 and the A-10. The supersonic jets, which will be able to conduct air-to-air and air-to-ground attacks, are just beginning to enter the Air Force fleet. Here, an F-35 Lightning II from the 34th Fighter Squadron at Hill Air Force Base, Utah, flys at Royal Air Force Lakenheath, England, April 15, 2017. Hide Caption 5 of 24 Photos: In the U.S. Air Force fleet B-2 Spirit bomber – The four-engine B-2 heavy bomber has stealth properties that make it hard to detect on radar. Flown by a crew of two, it has an unrefueled range of 6,000 miles and can deliver both conventional and nuclear bombs. Twenty B-2s are in the active inventory. They joined the fleet in 1997. Hide Caption 6 of 24 Photos: In the U.S. Air Force fleet B-1B Lancer bomber – The four-engine jet can fly at 900 mph and carry the largest payload of bombs and missiles in the Air Force inventory. The Air Force has 62 B-1Bs in the fleet. Hide Caption 7 of 24 Photos: In the U.S. Air Force fleet F-15 Eagle – The F-15 Eagle, the Air Force's main air superiority fighter, became operational in 1975. With a crew of one or two, depending on the model, the twin-engine jets are armed with a 20mm cannon along with Sidewinder or AMRAAM missiles. The Air Force lists 249 F-15 Eagles in its inventory. Hide Caption 8 of 24 Photos: In the U.S. Air Force fleet F-15E Strike Eagle – The Strike Eagle is a version of the air superiority fighter adapted to perform ground-strike missions. With a crew of two, the twin-jet can carry and deploy most weapons in the Air Force inventory and operate in any weather. The F-15E was first delivered in 1988. The Air Force lists 219 in its fleet. Hide Caption 9 of 24 Photos: In the U.S. Air Force fleet A-10 Thunderbolt – The A-10 Thunderbolt jets, nicknamed "Warthogs," are specially designed for close air support of ground forces. Key to their armaments is a 30mm Gatling gun. The pilot is protected from ground fire by titanium armor, and the plane's fuel cells are self-sealing in case of puncture. Hide Caption 10 of 24 Photos: In the U.S. Air Force fleet RC-135U – The RC-135U Combat Sent, based at Offutt Air Force Base, Nebraska, provides strategic electronic reconnaissance information to the president, secretary of defense, Department of Defense leaders and theater commanders. Hide Caption 11 of 24 Photos: In the U.S. Air Force fleet An F-15 Eagle takes off from the Andersen Air Force Base, Guam, flight line as two E-3 Sentries are seen in the background. Hide Caption 12 of 24 Photos: In the U.S. Air Force fleet OV-10 Bronco – A 21st Tactical Air Support Squadron OV-10 Bronco aircraft fires white phosphorus rockets to mark a target for an air strike during tactical air control training. Hide Caption 13 of 24 Photos: In the U.S. Air Force fleet A-29 Super Tucano – An A-29 Super Tucano taxis on the flightline during its first arrival, Sept. 26, 2014, at Moody Air Force Base, Georgia. Afghan Air Force pilots trained on the planes that will be used in air-to-ground attack missions in Afghanistan. Hide Caption 14 of 24 Photos: In the U.S. Air Force fleet KC-135 Stratotanker – The four-engine KC-135 joined the Air Force fleet in 1956 as both a tanker and cargo jet. It can carry up to 200,000 pounds of fuel and 83,000 pounds of cargo and passengers in a deck above the refueling system. More than 400 of the KC-135s are flown by active, Air Guard and Reserve units. Hide Caption 15 of 24 Photos: In the U.S. Air Force fleet F-16 Fighting Falcon – The single-engine jet is a mainstay of the Air Force combat fleet. It can perform both air-to-air and air-to-ground missions with its 20mm cannon and ability to carry missiles and bombs on external pods. More than 1,000 F-16s are in the Air Force inventory. Hide Caption 16 of 24 Photos: In the U.S. Air Force fleet C-17 Globemaster transport – The four-engine jet joined the Air Force fleet in 1993 with a primary mission of troop and cargo transport. Each plane can carry up to 102 troops or 170,900 pounds of cargo. The Air Force has 187 C-17s on active duty, 12 in the Air National Guard and 14 in the Reserve. Hide Caption 17 of 24 Photos: In the U.S. Air Force fleet C-5 Galaxy transport – The C-5, with a wingspan of 222 feet, a length of 247 feet and a height of 65 feet, is the largest plane in the Air Force inventory and one of the largest aircraft in the world. The first versions of the four-engine jet joined the force in 1970. The Air Force expects to have 52 versions of the latest model, the C-5M, in the fleet by 2017. Hide Caption 18 of 24 Photos: In the U.S. Air Force fleet CV-22 Osprey – The Osprey is a tiltrotor aircraft that combines vertical takeoff, hover and landing qualities of a helicopter with the normal flight characteristics of a turboprop aircraft, according to the Air Force. It is used to move troops in and out of operations as well as resupply units in the field. The Air Force has 33 Ospreys in inventory. Hide Caption 19 of 24 Photos: In the U.S. Air Force fleet E-3 Sentry AWACS – AWACS stands for airborne warning and control system. This four-engine jet, based on a Boeing 707 platform, monitors and manages battle space with its huge rotating radar dome. The planes have a flight crew of four supporting 13 to 19 specialists and controllers giving direction to units around the battle space. The Air Force has 32 E-3s in inventory. Hide Caption 20 of 24 Photos: In the U.S. Air Force fleet KC-10 Extender – Based on the DC-10 passenger jet, the triple-engine KC-10 is a gas station in the sky with the ability to carry 75 people and 170,000 pounds of cargo. In its six tanks, the KC-10 can carry up to 356,000 pounds of fuel and dispense it while airborne. The Air Force has 59 KC-10s on active duty. Hide Caption 21 of 24 Photos: In the U.S. Air Force fleet T-38 Talon – The twin-engine jet trainer, used by the Air Force to prepare pilots for the F-15E Strike Eagle, F-15C Eagle, F-16 Fighting Falcon, B-1B Lancer, A-10 Thunderbolt and F-22 Raptor, first flew in 1959. Almost 550 are in the active force. Hide Caption 22 of 24 Photos: In the U.S. Air Force fleet U-2 – The single-engine, single-pilot U-2 is used for high-altitude reconnaissance and surveillance. Flying at altitudes around 70,000 feet, pilots must wear pressure suits like those worn by astronauts. The first U-2 was flown in 1955. The planes were used on missions over the Soviet Union during the Cold War, flying too high to be reached by any adversary. The Air Force has 33 U-2s in its active inventory. Hide Caption 23 of 24 Photos: In the U.S. Air Force fleet WC-135 Constant Phoenix – The four-engine WC-135 is used to fly through airspace to detect the residue of nuclear blasts. "The aircraft is equipped with external flow-through devices to collect particulates on filter paper and a compressor system for whole air samples collected in holding spheres," the Air Force says. It has two of these jets in the active force. Hide Caption 24 of 24

"The US aircraft that have landed on South Korea include six F-22s, six F-35s, six EA-18Gs," a South Korean defense official told CNN. "More than 10 F-15Cs and F-16s have also been deployed for the drill."

These aircraft will stay in South Korea for the week. They will be joined by more F-35Bs -- the Marine Corps version, based in Japan -- B-1 bombers and E-3 airborne warning and control system (AWACS) aircraft that will fly in to join the war games and then return to bases elsewhere, the official said.

But it is the stealth fighters that experts say pose the biggest threat to Pyongyang.

While the North Korean military maintains capable anti-air weaponry, its radar systems would be unable to detect the F-22s and F-35s, which are cloaked with the world's most advanced stealth coating, before a strike on those defensive systems.

The North Korean commentary published in state newspaper Rodong Sinmun on Sunday said the aerial war games show "the enemies' moves to start a nuclear war have reached a dangerous stage."

"It is an open, all-out provocation against the DPRK, which may lead to a nuclear war any moment," it continued.

Another commentary published Monday referenced the succession of large-scale US-South Korean war games this year, including November's naval exercises that saw three US Navy aircraft carriers operate together in the Pacific for the first time in a decade.

It said war games are "driving the situation of the Korean Peninsula to the lowest ebb" and "bringing dark clouds of a nuclear war to the Korean Peninsula and Northeast Asia."

North Korean threat to US mainland

The exercises come less than a week after Pyongyang fired off an intercontinental ballistic missile it claims can reach the "whole" mainland of the United States.

A US official said Saturday technical analysis of that missile's flight is ongoing but the "the North Koreans had problems with re-entry."

It is likely the ballistic missile, fired higher than any previous North Korean missile, broke up as it re-entered Earth's atmosphere, the official said.

The crew from a Cathay Pacific flight reportedly saw the missile on its downward trajectory, the airline said in a statement Monday.

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Still, the ability of the new missile to fly higher and longer than others in the past signals North Korea's intent to develop weapons capable of attacking the US.

At the California forum, McMaster said Kim was extremely unlikely to change his behavior "without some significant new actions in the form of much more severe sanctions" and "complete enforcement of the sanctions that are in place."

He pushed China to do more, including cutting off North Korean oil imports.

"We're asking China not to do us or anybody else a favor," he said. "We're asking China to act in China's interest, as they should, and we believe increasingly that it's in China's urgent interest to do more."