U.S. President Donald Trump answers questions from the press before departing the White House in Washington D.C., United States on March 13, 2018. (Xinhua/Ting Shen)

SAN DIEGO, the United States, March 13 (Xinhua) -- U.S. President Donald Trump on Tuesday inspected prototypes for his long-promised wall along the border with Mexico in a tour that drew both supporters and protesters.

"If you don't have a wall system here, we're not gonna have a country," Trump warned while touring the eight prototypes of the wall he promised to build to keep out illegal immigrants near San Diego in the state of California.

His inspection of the prototypes made of concrete, steel and other materials marks his first visit to California since assuming office. He is also the first president since Dwight Eisenhower to skip a visit to the "Golden State" during the first year in office.

Since the construction work began in September, dispute between the White House and California, a Democratic stronghold that is at the forefront of resistance to his anti-immigration policy, has been fueling.

The president Tuesday showed his preference to the border wall that he promised to build in the 2016 presidential election, saying the wall should can be "see-through" and tall enough so that illegal immigration can not climb over.

"You have to have see-through," Trump said when he checked the prototypes, which are each 30 feet (9.1 meters) high and 30 feet (9.1 meters) long , standing 10 meters away from the old fence. "You have to know what's on the other side of the wall."

Trump described some people who illegally cross the border "like professional mountain climbers."

"They're incredible climbers. They can't climb some of these walls." he said, adding "Some of them they can. Those are the walls we're not using."

Trump also spoke to members of the Border Patrol about the old fence and the new wall, saying the old one, even though much more effective than nothing, could only deters about 95 percent of criminal activity, but the new wall is "going to stop 99 percent, maybe more than that."

U.S. President Donald Trump holds up before and after photos of a segment of the border inspects border wall prototypes in San Diego, California on March 13, 2018. / (Xinhua/AFP PHOTO)

Trump urged Congress at the prototype construction site to fund his long-promised border wall, which will cost 18 billion U.S. dollars according to the 10-year-period construction plan.

He claimed that the Mexican government will pay for the wall earlier and changed his words now that the wall will pay for itself since it will stop crimes from the other side.

"The border wall is truly our first line of defense," Trump said. "It will save thousands of lives, save taxpayers hundreds of millions of dollars by reducing crime, drug flow, welfare fraud and burdens on schools and hospitals."

"According to the Center for Immigration Studies, the $18 billion wall will pay for itself by curbing the importation of crime, drugs and illegal immigrants who tend to go on the federal dole..." he tweeted Tuesday morning.

U.S. President Donald Trump's supporters, like Jennifer Harrison, with megaphone, rally near the US-Mexico border for the presidential visit to California to view border wall prototypes in San Diego, California, U.S., March 13, 2018. (Xinhua/REUTERS)

A small group of supporters welcomed Trump's visit.

Jeff Schwilk, founder of San Diegans for Secure Borders, whose group participated in the December rally near the prototypes that ended in clashes with counterprotesters, said local residents feel the border is not secure.

"We absolutely want President Trump to feel welcome and to come inspect the prototypes so we can get the wall built," he said.

A woman walks with a slogan opposing border wall near the U.S.-Mexico border of in San Diego, the United States, on March 13, 2018. (Xinhua/Li Ying)

However, more local residents refused to follow the president's logic.

Kathleen Rooney, a local retiree living in San Diego, told Xinhua Tuesday that she doesn't think it's a good idea to build the wall between the United States and Mexico, which she said are good neighbors that "really rely on each other a lot."

"There's a tremendous amount of money that would be involved to build the wall and maintain and guard it," said Rooney. "Economically, it's really a poor decision."

Holding a banner that reads "We are all immigrants," Rooney was among dozens of protesters in downtown San Diego against Trump's harsh stances on immigration.

One of the rally's organizers, Rosi Escamilla, told Xinhua that she's concerned that the wall would be environmental harmful and cause more cultural division.

At least 200 people rallied and marched in downtown San Diego Monday in protest of Trump's policies. Some held signs read "build bridges, not walls,""No ban, no wall," and "No human is illegal."

"The wall shouldn't exist," said a protestor, Jude Santos, noting that the president with low approval ratings is only to get more support for his presidency.

"Mexico people are just looking for jobs to be able to feed their families. None of Americans wants to do those jobs with low salary," she added.

Kevin Faulconer, mayor of San Diego, posted a statement on his Twitter page, saying "biggest Welcome to San Diego, President Trump. Here you'll find a city that embraces its cross-border economy because free trade works."