Putting a number of conventional U.S. military forces into Syria is one of the options expected to be presented to President Donald Trump later this month as part of the effort to accelerate the defeat of ISIS, two senior U.S. defense officials told NBC News on Thursday.

The troops would be sent in to serve as enablers, force protection and engineering advisers — similar to the way the United States has worked alongside the Iraqi Security Forces in Iraq.

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The numbers of additional troops would likely be hundreds, the officials said.

The United States does already have conventional forces operating in Syria. However, under the Obama administration, the rules for how many troops are allowed in the country have been very specific and set by the White House. For example, the last increase allowed 203 more troops to operate in Syria.

Some troops had to deploy into the country for short periods of time — fewer than 30 days — leave and then go back so they were never counted in overall troop numbers.

But the possible new proposal could mean that most of the forces who typically rotate in and out for short durations would stay in country and build out an operating location or forward operating base.

Defense officials stressed that none of the options are final, that none have been presented to Trump and that they have no idea what he will decide. With Trump being so new to the office, the officials would not speculate on his possible decisions.

They also stressed that the mission or the ultimate objective had not changed, but they said it's possible Trump could change some element of it as part of the 30-day review.