A mine detection team is seen on the road leading to Hanoi. Photo by VnExpress/Gia Chinh

On Sunday, army officers and security forces were on guard from early morning at all junctions, intersections, residential areas and construction sites along National Highway 1A from Hanoi to the northern mountainous province of Lang Son.

Sidewalks and median strips on the 200km long road were swept by sapper forces with specialized mine detection equipment.

North Korea’s Korean Central News Agency (KCNA) confirmed Sunday that the North Korean leader Kim Jong-un has boarded a train in Pyongyang to Hanoi for the second summit with the U.S. President Donald Trump and for his first official visit to Vietnam.

With just three days to go before the historic second summit, security has been heightened to the highest level along major streets from Noi Bai Airport to Hanoi and at five-star hotels in the city center.

Sapper forces check bombs and mines inside the five-star JW Marriott Hotel in Hanoi on Sunday morning. Photo by VnExpress/Pham Du

On Sunday, police officers stood guard in front of the five-star JW Marriott Hotel on Do Duc Duc Street in Hanoi's Nam Tu Liem District, while a group of sapper staff carried out their checks on the hotel premises.

Security cameras have been installed all along the street.

More than 200 U.S. Secret Service agents showed up in Hanoi Saturday morning, and their car fleet was seen stopping at JW Marriott Hotel.

A U.S. secret agent stands at JW Marriot Hotel in Hanoi on Saturday afternoon. Photo by VnExpress/Ngoc Thanh

A delegation of North Korean security agents arrived in the capital city Sunday morning and came to Melia Hotel in the city center.

A large police contingent numbering tens of thousands of officers have been deployed to maintain order and security during the summit, patrolling roads and the vicinities of hotels, train stations and airports.

Hanoi has asked the Ministry of Public Security to send more personnel to better distribute security forces.

A mobile police officers stand guard in front of the JW Marriot hotel where the U.S. delegation is expected to stay during the upcoming summit. Photo by VnExpress/Pham Du

The first Trump-Kim summit was held in Singapore last June, but negotiations failed to achieve much owing to disagreements over the concept of denuclearization.

Both sides are hoping to make more headway at the upcoming summit.