The US has put sanctions on a Chinese firm and four executives over allegedly helping North Korea evade sanctions.

Dandong Hongxiang is accused of acting on behalf of a North Korean bank that is on a UN sanctions list to stop the spread of weapons of mass destruction.

The sanctions come after North Korea sparked a global outcry this month by conducting its fifth nuclear test.

The engineering company and its bosses are also under investigation by Chinese authorities.

The US decision to extend sanctions on the industrial machinery and equipment wholesaler means that American companies or individuals are banned from doing business with the Chinese company or the four executives.

Aside from the firm's founder, Ma Xiaohong, the sanctions include Zhou Jianshu, Hong Jinhua and Luo Chuanxu, who are accused of conspiring to violate sanctions rules and engaging in international money laundering.

According to Adam Szubin, the Treasury Department's acting under secretary for terrorism and financial intelligence, Dandong Hongxiang was instrumental in a "key illicit network supporting North Korea's weapons proliferation," acting on behalf of North Korea's Kwangson Banking Corp.

The Chinese company and its employees "sought to evade US and UN sanctions, facilitating access to the US financial system by a designated entity," he said in a statement.

The US Justice Department said bank accounts associated with the firm and front companies received hundreds of millions of dollars that transited through the US.

SEOUL, South Korea — The United States on Wednesday flew a pair of supersonic bombers over ally South Korea for the second time in as many weeks in a show of force following North Korea's latest nuclear test earlier this month.

U.S. Forces Korea said one of the two B-1B bombers landed at Osan Air Base, 120 kilometers (75 miles) from the border with North Korea, but did not say when it will return to Andersen Air Force Base in Guam.

Such flyovers are common when animosity rises on the Korean Peninsula, which is technically in a state of war because the 1950-53 Korean War ended with an armistice, not a peace treaty. The United States also flew two B-1B bombers over South Korea on Sept. 13.

"What we are showing today is just one tool we have to choose from a wide array of options. The alliance grows stronger every day and we remain prepared to defend and to preserve the security of the Korean Peninsula and the region," Lt. Gen. Thomas Bergeson, commander of the U.S. 7th Air Force in South Korea, said in a statement.

North Korea uses such flyovers and the American military presence in the South in its propaganda as alleged proof of U.S. hostility, which it says is the reason it needs a nuclear weapons program. After last week's flyover, North Korea's official Korean Central News Agency described the B-1B as an "ill-famed nuclear war means" and accused the United States of resorting to "nuclear threat and blackmail" against the North.

The B-1B doesn't currently carry nuclear weapons under a disarmament treaty, and some U.S. experts do not consider them as nuclear capable in their current configuration.

Military experts raise concerns that North Korea is moving closer toward obtaining the ability to put nuclear warheads on a variety of its ballistic missiles, a growing arsenal that one day may include a reliable weapon that could reach the U.S. mainland.

LOS ANGELES -- A 19-year-old Marine from Camp Pendleton who was shot this weekend while visiting friends and family in South Los Angeles died Monday night, coroner's officials said.

Carlos Segovia died at 8 p.m. at California Hospital Medical Center, according to the Los Angeles County Medical Examiner-Coroner. Segovia had been hospitalized in grave condition since the weekend.

He was found at 11:35 p.m. Friday slumped over and unconscious in a Dodge Charger in the 2100 block of 31st Street, according to Capt. Peter Whittingham of the Los Angeles Police Department.

The Marine left the military base near San Diego on Friday. He had just visited his girlfriend that night and was preparing to drive to the home of Claudia Perez, a family friend, when he was struck by gunfire.

Perez said Segovia was like her child and he usually stayed at her home when he visited the area.

"He texted my son that he was bringing pizza home," she said. "He never made it."

Friends and family will hold a vigil for Segovia at 6:30 p.m. Tuesday at the site of the shooting, police said.

No suspect has been identified in the shooting. Police said Segovia has no connections to gangs or other activity that would seem to make him a likely target of gun violence.

Whittingham said the shooting is "absolutely a mystery."

"Like so many cases in South L.A., we have nothing to go on at this point," he said.

Segovia, who was born in El Salvador, came to the U.S. with his mother. Both are U.S. citizens, Perez said.