WASHINGTON — President Donald Trump on Wednesday started to reshape U.S. immigration enforcement policies via executive action, taking his first steps toward fulfilling some of the most contentious pledges that defined his campaign — building a border wall and punishing “sanctuary cities.”

Trump signed executive orders ordering the construction of a wall on the U.S.-Mexico border, boosting border patrol forces and increasing the number of immigration enforcement officers who carry out deportations.

“Beginning today, the United States of America gets back control of its borders,” Trump told employees of the Department of Homeland Security at the department’s headquarters in Washington.

But while Trump directed the “immediate construction of a physical wall on the southern border,” the executive orders do not cover the cost of the wall. Trump has repeatedly said Mexico will reimburse US taxpayers for the construction costs.

Wednesday’s executive orders also seek to end sanctuary cities by stripping grant funding for those cities and ends the practice of releasing undocumented immigrants detained by federal officials before trial.

The president’s moves sent alarm bells ringing in immigrant activist circles, where questions had continued to swirl about whether Trump would truly implement many of the hard-line immigration policies he articulated during his campaign.

Trump also indicated he does not need Congress to pass new legislation to implement the border control and immigration reform agenda he outlined during his campaign for president.

“We do not need new laws. We will work within the existing system and framework,” Trump said soon after he signed the two executive orders focused on border security and immigration enforcement.

RELATED: Executive order on border security
RELATED: Executive order on enforcement of immigration laws

The executive orders Trump signed Wednesday call for boosting the ranks of Border Patrol forces by an additional 5,000 agents as well as for 10,000 new Immigration and Customs Enforcement officers to carry out deportations.

The orders noted the increases were subject to Congress’s appropriation of sufficient funds.

Construction of the wall could begin in months, but planning for the massive project is “starting immediately,” Trump said Wednesday in an interview with ABC News.

Trump confirmed his plans to build the wall with federal funds and then seek reimbursement from Mexico, an idea Mexico has rejected. But negotiations, he said, would begin “relatively soon.”

“I’m telling you there will be a payment. It will be in a form, perhaps a complicated form,” Trump said.

Trump also for the first time appeared to articulate the argument he might make to Mexican officials as he looks to compel them to pay for the wall.

Trump stressed the wall would “help Mexico” by deterring illegal immigration from countries farther south through Mexico.

“We are going to stabilize on both sides of the border and we also understand that a strong and healthy economy in Mexico is very good for the United States,” Trump said.

Trump’s actions leave little doubt about whether his immigration policies as president would differ from his campaign rhetoric.

There remained little question, for example, about whether Trump would push to increase deportations of undocumented immigrants.

One of Trump’s executive actions was expected to call for tripling “enforcement and removal operations/agents” of the Immigration and Customs Enforcement agency, which is charged with arresting and deporting undocumented immigrants living in the U.S.

The order also calls for an 5,000-person increase in Customs and Border Protection personnel.

Marielena Hincapie, executive director of the National Immigration Law Center, called Trump’s actions Wednesday “extremist, ineffective and expensive” and accused the president of using lies about immigrants to drive U.S. policy.

“Trump is taking a wrecking ball to our immigration system. It shouldn’t come as a surprise that chaos and destruction will be the outcome,” Hincapie said, adding that her organization has already drafted legal papers to challenge Trump’s moves.

And Greisa Martinez, advocacy director at the United We Dream Network, argued that Trump’s moves “lay the groundwork for mass deportation.”