The Pentagon has started hunting for sites along the U.S.-Mexico border to install new physical barriers, CNN reported Thursday quoting two defense department officials.

Under the instruction of the department, a group of engineers started inspecting various sites in Yuma, Arizona, and the New Mexico portion of the El Paso sector, including Texas, on Wednesday. Each assessment is likely to take around seven days, which will be followed up by a formal engineering survey in April after awarding contracts to the builders. The installation should begin by late May which will be funded by the $1 billion transferred by the Department of Defense recently under President Donald Trump ’s national emergency declaration.

Speaking to CNN, Jay Field, a spokesperson for the U.S. Army Corps of Engineers, confirmed the news saying they were planning to install 46 miles of fencing at El Paso and 11 miles at Yuma.

The move comes a few days after Pentagon announced it was transferring $1 billion from a military personnel account in order to install 57-mile fencing along the U.S.-Mexico border, as well as improving roads and other measures in the region. According to a letter sent by acting Secretary of Defense Patrick Shanahan to Secretary of Homeland Security Kirstjen Nielsen, the funds will be directed toward installing an 18-foot-high fencing along the Yuma and El Paso sections of the border.

In a letter to Shanahan, the Senate Democrats spoke against the transfer of money stating they "have serious concerns that the Department has allowed political interference and pet projects to come ahead of many near-term, critical readiness issues facing our military," the Hill reported.

Trump claimed the country was facing national emergency at the southern border and renewed his attack on Democrats for not supporting his immigration policies.

“We have a National Emergency at our Southern Border. The Dems refuse to do what they know is necessary - amend our immigration laws. Would immediately solve the problem! Mexico, with the strongest immigration laws in the World, refuses to help with illegal immigration & drugs!” Trump tweeted Thursday.

Earlier this month, the POTUS vetoed Congress’ effort to reverse his national emergency declaration, allowing the administration to spend more money on building border barriers.