North Korea’s neighbors are steeling themselves for more provocative action from Kim Jong Un’s regime, with Japan’s prime minister raising the prospect of a chemical weapons attack and South Korea’s military saying it is ready to “mercilessly retaliate.”

Expectations remain high that North Korea will conduct another nuclear or missile test, or carry out some other incendiary act, to mark the most important day on its calendar: the anniversary Saturday of the birthday of Kim Il Sung, the country’s founder, and the current leader’s grandfather. 

The worries reflect a deepening anxiety in the region amid the North’s military bluster and tough talk from President Trump.

Echoing a tweet earlier this week, Trump wrote Thursday on Twitter that he believes China will be able to rein in the North, which depends on Beijing for nearly all its foreign commerce and aid.

“I have great confidence that China will properly deal with North Korea,” he wrote. “If they are unable to do so, the U.S., with its allies, will! U.S.A.”

(Jason Aldag/The Washington Post)

Japanese Prime Minister Shinzo Abe said Thursday that he is worried that North Korea could be developing its chemical weapons capability — with Japan as its target.

“It’s possible that North Korea might already have the ability to deliver sarin warheads on missiles,” Abe told a parliamentary committee.

The prospect of a sarin attack is particularly sensitive in Japan, where a doomsday cult used the nerve agent on the Tokyo subway in 1995, killing 12 people. 

Concerns have been growing about North Korea’s chemical weapons capabilities since Kim Jong Nam, Kim Jong Un’s estranged half brother, was killed with the nerve agent VX in Malaysia in February.

“North Korea is thought to maintain multiple facilities that are capable of producing chemical weapons and already hold a sizable amount of chemical weapons,” Yoshihide Suga, Abe’s top aide, told reporters after a meeting of Japan’s national security council.

(White House)

Meanwhile, the new commander of South Korea’s Marine Corps, Lt. Gen. Jun Jin-goo, called on his 30,000 troops to be ready to “mercilessly retaliate” against any North Korean provocations, according to the Yonhap News Agency.

Kim Jong Un looked relaxed Thursday when he appeared at the opening ceremony for one of his marquee projects: the Ryomyong Street development in Pyongyang. The district, with its high-rises and fancy stores, has become a symbol of North Korea’s purported economic development and improved standard of living under Kim.

The most recent satellite images of North Korea’s underground nuclear test site, at Punggye-ri in the northeast, show it is “primed and ready,” according to the 38 North website, which follows North Korean affairs.

People and vehicles continue to move around the site, according to images from Wednesday, the report said. There have been varying amounts of activity, including the removal of rubble and draining of water, over the past two weeks, raising concerns that North Korea might be preparing for its sixth nuclear test. 

North Korea has also been firing missiles at a steady clip, and from mobile launchers that are rolled out of tunnels or hangars immediately before launch and are, therefore, difficult to spot by satellite. 

In 2012, two days before the 100th anniversary of Kim Il Sung’s birthday, North Korea tested a long-range missile. It broke up soon after launch.

North Korea sometimes seems to enjoy stoking its adversaries’ fears. There were similarly high expectations around a big anniversary in October, but North Korea did nothing. 

Still, doing something provocative in the next few days would have another benefit for North Korea: It would send a clear message to Vice President Pence, who is to arrive in Seoul on Sunday.  

Pence, who also will travel to Tokyo, is expected to reiterate Trump’s tough messages on North Korea, which have been backed up by the deployment of an aircraft carrier to the waters off the Korean Peninsula. 

This signaling by the Trump administration, coming after last week’s U.S. missile strike on a Syrian air base and Trump’s attempt to pressure China to deal with North Korea, has led to widespread conjecture about an American military strike on North Korea. 

Politicians in Japan and South Korea — both U.S. security allies — have voiced concern that their countries could become retaliatory targets for North Korea. 

There is particular nervousness in South Korea. The North has conventional artillery trained on Seoul and its commuter belt, home to more than 20 million people. 

South Korean presidential candidates from across the political spectrum insisted in a debate Thursday that the United States not launch any action against North Korea without consulting the South. South Korea will hold a snap election May 9.

Japan’s Foreign Ministry issued a travel warning for its citizens in South Korea this week, asking them to “pay attention to the situation on the Korean Peninsula.” 

But analysts in the region say there is a low chance of U.S. military action against North Korea. 

“This is all psychological warfare,” said Narushige Michishita, a North Korea specialist at the National Graduate Institute for Policy Studies in Tokyo.  

“It’s ostensibly about North Korea, but it’s also about China,” he said. “Trump seems to be creating a situation where he can put China on the defensive and coerce them into action.”

Trump said this week that he had offered Chinese President Xi Jinping better trade terms if he cracked down on North Korea.

Robert Kelly, a professor of international relations at Pusan National University in South Korea, said the Trump administration was trying to send a message to China. “There is a sense that China is not taking this as seriously as a lot of us on the outside want them to,” he said. 

But Kelly was skeptical that this tactic would work. “My sense is that China doesn’t respond well to overt public threats, that China much prefers backroom talks,” he said. 

Even while supporting some sanctions, China’s top priority has always been maintaining stability in North Korea. Beijing does not want the regime there to collapse, possibly sending millions of hungry North Koreans into northeastern China and potentially enabling the U.S. troops now in South Korea to move up the peninsula to the Chinese border. 

But China has appeared to take some action this week. The country reportedly has rejected some North Korean coal shipments, and a state-linked paper warned that China would restrict oil imports “if the North makes another provocative move this month.”