A U.S. Border Patrol agent stands in front of the border fence that divides the U.S. and Mexico in San Diego, California, the United States, Nov. 17, 2018. Officers of the U.S. Customs and Border Protection (CBP) have tightened preparations at the U.S.-Mexico border in San Diego, California, for the arrival of massive caravans of Central American migrants.(Xinhua/Zhao Hanrong)

SAN DIEGO, The United States, Nov. 17 (Xinhua) -- Officers of the U.S. Customs and Border Protection (CBP) have tightened preparations at the U.S.-Mexico border in San Diego, California, for the arrival of massive caravans of Central American migrants.

In the Border Field State Park, which is on the very southwestern corner of the United States and 15 miles (24 km) south of San Diego, CBP personnel set up wire protection net on the border fence on Friday.

Ryan Gosalves, an officer of CBP, told Xinhua they work around the clock at the Imperial Beach, with 20 agents on duty in each shift.

A total of 400 CBP agents were deployed at the Imperial Beach, which has a 6.5-mile (9.8 km) borderline with Mexico, he said, adding there were 2,200 agents in all at U.S.-Mexico border across the country.

Remote monitors and camera towers were set up along the border at the Imperial Beach to watch for migrants, Gosalves said.

The U.S. government has said that immigrants who enter the country illegally would be banned from applying for asylum.

U.S. President Donald Trump has categorized the caravan as an "invasion" and ordered the U.S. Department of Defense to deploy active-duty troops to the border in assistance to border security forces.

At least 1,800 migrants, mainly from Honduras, have arrived in groups in the Mexican border city of Tijuana this week. More are expected to arrive since they are currently traveling in nearby towns, authorities said.

Authorities from Mexico and the United States met in Tijuana on Friday to coordinate plans prior to the arrival of massive caravans of Central American migrants.