SEOUL, South Korea — Emphasizing diplomacy and sanctions over war, the top American general and South Korea’s president said on Monday that they hoped to avoid armed conflict with North Korea, as China vowed to enforce new United Nations penalties.
The developments suggested that officials of the United States, South Korea and China are seeking to emphasize a message in Asia of lowering tensions after President Trump’s apocalyptic threats last week over North Korea’s missile and nuclear testing.
In a meeting with President Moon Jae-in of South Korea, whose country has been alarmed by Mr. Trump’s threats, Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff, said military options were a last resort.
“The United States military’s priority is to support our government’s efforts to achieve the denuclearization of the Korean Peninsula through diplomatic and economic pressure,” General Dunford was quoted as saying in a Korean-language statement released by Mr. Moon’s office after the meeting. “We are preparing a military option in case such efforts fail.”
General Dunford’s remarks were echoed by Defense Secretary Jim Mattis and Secretary of State Rex W. Tillerson, who co-wrote an opinion column posted online Sunday by The Wall Street Journal asserting that the United States and its allies wanted a peaceful resolution.
Without mentioning Mr. Trump’s “fire and fury” and “lock and load” threats to North Korea, they wrote that the administration was applying “diplomatic and economic pressure on North Korea to achieve the complete, verifiable and irreversible denuclearization of the Korean Peninsula and a dismantling of the regime’s ballistic-missile programs.”
Before the meeting with General Dunford, Mr. Moon issued one of his strongest statements yet against armed conflict. “Our national interest is peace, and there should never be war on the Korean Peninsula again,” Mr. Moon was quoted as saying in a meeting with his senior staff. “No matter what it takes, the North Korean nuclear problem must be resolved peacefully.”
In China, North Korea’s main trading partner, officials announced that they would begin enforcing tough new United Nations sanctions against Pyongyang on Tuesday.
General Dunford’s visit to South Korea was the first of three stops in his trip to the region, which has been roiled by the exchange of fiery threats between Mr. Trump and the North Korean leader, Kim Jong-un.
The general has said that the trip is meant to offer transparency to America’s allies in the region and to prevent any miscalculation on China’s part about the Pentagon’s intentions. He arrived in China on Monday night, and will travel to Japan later in the week.
South Koreans, many living within range of North Korean artillery, were particularly alarmed by Mr. Trump’s threat to bring down “fire and fury” on the North if Pyongyang continued to threaten the United States with nuclear missiles.
On his way to Seoul, General Dunford said his trip was in support of Mr. Tillerson’s diplomatic and economic campaign to deter North Korea. Even as Mr. Trump has issued one provocative statement after another against the North, Mr. Tillerson has been reminding Pyongyang that the door to dialogue is open if the nation halts missile and nuclear tests.
“As a military leader, I have to make sure that the president does have viable military options in the event that the diplomatic and economic pressurization campaign fails,” General Dunford told reporters on his plane. “But even as we develop those options, we are mindful of the consequences of those options, and that gives us a greater sense of urgency to make sure we are doing everything we absolutely can to support Secretary Tillerson’s path.”
The general’s calibrated statement appeared to be an attempt to calm allies in South Korea while backing up Mr. Trump’s warnings to the North.
Concern escalated in the Trump administration about the North’s nuclear threat after the country flight-tested two intercontinental ballistic missiles last month, the second of which appeared to have the capacity to reach the American mainland. It is not clear that the North can accurately target such a missile or build a nuclear warhead that can survive re-entry into the atmosphere.
This month, Washington persuaded China and Russia to agree to the toughest United Nations Security Council sanctions to date against North Korea, which could deprive it of as much as a third of its external export revenues.
On Monday, China’s Ministry of Commerce and customs administration announced that the country would begin enforcing the sanctions on Tuesday, by fully banning imports of aquatic products, coal, iron, iron ore, lead and lead ore from North Korea. The seafood products it listed as banned include fish, crustaceans and sturgeon caviar. Seafood, along with coal, has been a sizable Chinese import from North Korea.
China imported $91 million worth of seafood from North Korea in the first half of 2017, according to Chinese customs figures cited by Reuters.
China’s announcement came hours before General Dunford was scheduled to arrive in Beijing. He was scheduled to meet with Gen. Fang Fenghui, his Chinese counterpart, during his two-day visit, Pentagon officials said.
The visit to China was planned well before the recent North Korea developments, as part of a choreographed series of visits of top American and Chinese generals to each other’s countries. General Fang visited Washington in 2014.
In Beijing, General Dunford is expected to emphasize that Washington plans to complete the deployment of a missile defense system known as Thaad in South Korea. China has vehemently opposed the deployment, calling it a threat to Chinese security.
Speaking to South Korea’s National Assembly on Monday, Defense Minister Song Young-moo said his military hoped to complete the Thaad deployment by the end of the year.
North Korea showed no sign of dialing down its rhetoric on Monday. In a statement denouncing annual joint exercises between the United States and South Korean militaries, which are scheduled to begin on Aug. 21, the North’s official Korean Central News Agency warned that a second Korean War would be a “nuclear war.”
“Even if no one wanted it, they would not be able to prevent a mere accidental spark from triggering a war,” the statement said.
North Korea strongly objects to the joint military exercises, calling them a rehearsal for an invasion, and has often responded to them with weapons tests. China has proposed that the joint exercises be suspended in exchange for a suspension of the North’s nuclear and missile tests, but Washington has rejected the idea.
Lee Jin-woo, a spokesman for the South Korean Defense Ministry, said on Monday that the joint exercises would go ahead as planned, denying a domestic news media report that they would be scaled down this year.
The North Korean military has said it will complete a plan to launch four ballistic missiles in waters around Guam, home to a major American Air Force base in the Western Pacific, by the middle of this month, and will then wait for Mr. Kim’s order to proceed. It has also claimed that 3.5 million young North Koreans have recently volunteered to join the military to fight the Americans.
In China, the overseas edition of the People’s Daily, the ruling Communist Party’s main newspaper, said on Monday that the world had become used to belligerent statements from North Korea, but had been alarmed to hear similarly aggressive talk from the United States.
An editorial in the paper warned that the joint military exercises between the United States and South Korea would only make the situation worse. The overseas edition of the People’s Daily is a lower-circulation offshoot of the main domestic edition, and its editorials broadly reflect official thinking.
“It’s to be feared that this will became a new goad for North Korea, and trigger another round of tit-for-tat confrontation,” the editorial said, referring to the joint exercises. “It is not advisable to play chicken on the Korean Peninsula. All sides should be careful in their words and actions.”
Chris Buckley and Jane Perlez contributed reporting from Beijing.