U.S. soldiers put up concertina wire along the Gateway International Bridge in Brownsville, Tex., in November. (Alexandra Minor/AFP/Getty Images)

About 3,500 additional U.S. troops will deploy to the southern border, the chairman of the House Armed Services Committee said Thursday, criticizing the Pentagon for not revealing the number a day earlier under questioning at a committee hearing.

Rep. Adam Smith (D.-Wash.), the committee chairman, said he was “deeply troubled” that John Rood, the undersecretary of defense, and Vice Adm. Michael Gilday, the director of operations for the Pentagon’s Joint Staff, did not disclose the increase in U.S. troops, “even though we asked them multiple times during a two-and-a-half-hour hearing what would happen next at the border.”

“They never mentioned it, despite the fact that the Secretary of Defense was revealing an increase in personnel that same day,” Smith said in a statement, referring to acting Pentagon chief Patrick M. Shanahan. “This was at best an error in judgment, and at worst flat-out dishonesty.”

Smith, in a letter to Shanahan also released Thursday, said the Defense Department “balked” when given an opportunity to testify about the border mission. It marks a shot across the bow that Democrats will be pressing the Pentagon for more information now that they control the House.

“In my opening statement before yesterday’s hearing, I said one of the goals of the hearing was to ‘set the factual record straight about the Department’s support on the southern border,” Smith said in the letter. “We did not achieve that goal with the testimony provided by Secretary Rood.”

During the hearing, Smith did not specifically ask how many additional troops were going to the border, though he requested an update on what would be occurring.

Spokesmen for Rood and Shanahan could not immediately be reached for comment on Thursday.

A U.S. defense official, speaking on the condition of anonymity because of the sensitivity of the issue, said the number Smith announced in his statement on Thursday is roughly accurate and has been discussed internally at the Pentagon for several days.

The committee hearing was held Wednesday morning just after Shanahan held his first news conference with Pentagon reporters. Shanahan said then “several thousand” additional U.S. troops would deploy to the border, supplementing about 2,300 already there. However, Shanahan did not provide a specific number.

An additional 3,500 active-duty U.S. troops will put about 5,800 on the southern border, just short of the 5,900 the Pentagon had there in November. Those service members were dispatched in response to a request from the Trump administration as thousands of migrants traveling from Central America made their way north through Mexico.

The deployment, announced just before the midterm elections, was decried as a political stunt by Democrats and some retired generals, a claim the Pentagon denied. Many of the migrants said they wanted to legally apply for asylum in the United States at a port of entry.

Trump has continued to highlight the involvement of the U.S. military on the border as he presses to meet a campaign promise to build a border wall.

“More troops being sent to the Southern Border to stop the attempted Invasion of Illegals, through large Caravans, into our Country,” Trump tweeted Thursday. “We have stopped the previous Caravans, and we will stop these also. With a Wall it would be soooo much easier and less expensive. Being Built!”