A top defense analyst said Friday that a leaked document allegedly showing President Trump's 2018 defense budget appears to be authentic.

The figures posted by Third Way show a budget that doles out a 4 percent increase over the Obama administration's projections to each of the military services equally, said Todd Harrison, the director of defense budget analysis at the Center for Strategic and International Studies.

Most of the increases would go to training, equipment maintenance and other areas to increase military readiness, while procurement of weapons systems such as fighter jets and ships would see a slight decrease, Harrison said.

If authentic, the May 8 spreadsheet is an extraordinary dump of budget data just days before the White House is expected to unveil its plans on Tuesday, which will include detailed spending proposals for the entire federal government.

Third Way said it received the document earlier this week.

"You never know if the data has been tampered with or something like that, but looking at the data myself it looks consistent with what they've told us would be in the budget," Harrison said.

The coding on the data also looks to be consistent with documents produced by the White House Office of Management and Budget, Harrison said.

The White House could have made changes to its budget plan since May 8, but significant changes would be unlikely due to the short time period until the expected official release Tuesday, he said.

Bloomberg and Defense News also received leaked budget figures this week indicating modest increases and a defense plan that tracks closely with Obama administration projects.

Trump has promised a historic military buildup with significantly more troops, aircraft and ships, but that is likely not possible in 2018 with the $603 billion total defense baseline spending figure the White House released in March as part of its so-called "skinny" budget, according to analysts.

The administration has also proposed offsetting defense spending with major cuts to nondefense programs in an effort to rein in public debt.

The leaked document details a 3 percent increase for military personnel, a 2.1 percent increase for operations and maintenance and a 10 percent increase for research and development, Harrison said. The increases are compared with the 2018 spending projected last year by the Obama administration.

"They're putting their money into force structure and capacity," Harrison said.