President Trump's defense budget proposal for 2018 essentially follows Obama administration plans and adds only slightly more funding, the Republican chairman of the House Armed Services Committee said Monday.

Rep. Mac Thornberry, R-Texas, declined to say how much additional defense spending his committee will recommend as part of its annual policy bill, which could be completed this summer, but he has personally proposed nearly $40 billion more in total baseline defense spending than Trump.

The White House is set to unveil its first full-year budget proposal Tuesday, including a roll-out by the military services at the Pentagon. It will propose $603 billion in baseline defense spending, which includes the nuclear arsenal, and $65 billion for overseas war operations.

"I think that the budget that the administration will propose is roughly 3 percent more than what President Obama had suggested for this year. It's roughly a 5 percent increase over current year funding," Thornberry said while speaking at the Brookings Institution. "So, I think it is fair to say it's basically the Obama approach with a little bit more, but not much."

Trump has promised a historic military buildup, including big increases in the number of ships, aircraft and troops. But analysts have questioned whether the top-line spending unveiled earlier this year by the White House will move the United States in that direction in 2018.

The budget release is expected to shed light on how the Trump administration would use the increased funding and could also provide military buildup plans for the coming years.

Thornberry, who along with Sen. John McCain has been critical of the budget plans for months, said Monday the U.S. should look to the seven years of 10 to 18 percent defense spending increases in the 1980s under President Ronald Reagan.

"That is what it took to overcome the neglect and damage done in the 1970s to our military and I think that sort of context kind of helps us with the size and the duration of what sort of repair work that is needed for the problems that we face," Thornberry said.