President Xi Jinping spent the second day of his Guangdong tour visiting a military base, where he called on marines to improve combat readiness and stay vigilant. He also toured Shantou, the hometown of many overseas Chinese, on Tuesday.

The president will take part in celebrations to mark the 40th anniversary of the Shenzhen special economic zone
on Wednesday.

At the military base near Shantou in the east of the province, Xi told marines they should aim to be a “multifunctional, rapid response, all-weather and region” fighting force.

“[You should] focus your minds and energy on preparing to go to war, and stay highly vigilant,” Xi said, according to state broadcaster CCTV.

“Marines have many different missions and the demands on you will vary,” he said. “As such [you] should base your training on [the need to] go into battle … and raise [your] training standards and combat ability.”

Xi, who is also chairman of the Central Military Commission, told the marines they should shoulder the “important responsibility” of safeguarding Chinese territory and sovereignty, the country’s maritime interests and its interests overseas – veiled references to Beijing’s claims to Taiwan and the South China Sea.

The visit comes as tensions rise across the Taiwan Strait and amid warming ties between the US and Taiwan, the self-ruled island that Beijing has vowed to bring under its control, by force if necessary.

Foreign ministry spokesman Zhao Lijian on Tuesday said Beijing would retaliate in response to reports that the US Congress was reviewing three deals to supply Taiwan with advanced weaponry.

“The United States should immediately cancel the planned weapon sales to Taiwan, stop any arms deals and cut off their military ties,” Zhao said.

Xi visited Shantou in the afternoon, where he said China would achieve its goal of “national rejuvenation” despite the challenges it faced.

In video footage posted by social media users, Xi is seen in Shantou saying that he will emphasise in Shenzhen that China will “unswervingly follow the path of reform and opening up, and continue to build a prosperous and modern Chinese nation”.

Shantou is one of the four special economic zones set up by Beijing in its early days of reform but it has lagged behind Shenzhen, which went on to become China’s hi-tech hub.

However, speaking to residents on Tuesday, Xi praised overseas Chinese for their contributions to the country’s reforms. Many well-known tycoons were born in Shantou and nearby Chaozhou – which Xi visited on Monday– including billionaires like Li Ka-shing, Tencent founder Pony Ma Huateng and Gome founder Huang Guangyu.

In Shenzhen, Xi is expected to meet officials from cities in the Greater Bay Area development zone. He will also meet Hong Kong Chief Executive Carrie Lam Cheng Yuet-ngor and her Macau counterpart Ho Iat-seng.

The president’s Guangdong tour comes just two weeks before an important Communist Party plenum during which the next five-year economic and social development plan is expected to be approved.

Zhang Siping, a former deputy mayor of Shenzhen, said as Beijing sought to open the country further, the city would again be tasked with achieving a “breakthrough” as it did 40 years ago.

“But the ‘breakthrough’ mission is totally different now,” he said, adding that it would become the “pilot zone for socialism with Chinese characteristics”.

“Against the backdrop of sanctions, containment and decoupling from the US, Shenzhen will need to make breakthroughs in setting new rules, systems and standards, and make China’s economy more integrated with the world’s,” said Zhang, founder of the Shenzhen Innovation and Development Institute, an independent think tank.

He said Shenzhen would have to reinvent itself and adjust its export-oriented focus in line with the new emphasis on both the international and domestic markets.

Wu Junfei, deputy director of Hong Kong think tank the Tianda Institute, said Xi’s stops in Chaozhou and Shantou had sent a “subtle message” to Chinese entrepreneurs.

“We all know that many top businessmen were born in that area and they have close connections. Many top business leaders in Shenzhen also come from that area, so [the visits are] like a gentle pat on the back,” Wu said.