Republicans used the renewed attention on the region to sharply criticize the previous administration. Sen. Tom Cotton said former President Barack Obama's handling of Afghanistan has been "muddling along" in the region, but deferred to Trump's adviser and the commander-in-chief to reach a final decision.
"It's been clear for a while that we have not had the forces on the ground in Afghanistan to accomplish our mission there," Cotton told "The Hugh Hewitt show" on Tuesday.
Senate Armed Service chairman John McCain recalled an instance when the military was unable to maintain aircraft in Afghanistan and had to pay $50 million to contractors.
"That's how stupid this administration, the Obama administration was," the Arizona Republican told reporters Tuesday. "And all of those people who love Obama -- he's responsible for it and it's disgraceful and I'm outraged by it."
The final proposals for a planned troop increase in Afghanistan are expected to cross Trump's desk this week. US officials say the likely range for the US troop increase in Afghanistan is between 3,000 and 5,000 troops, but could be as low as 1,500. The increase would be to accelerate training missions for Afghan forces and well as to fight the Taliban. It is unclear when Trump will make a formal decision.
Democrats expressed skepticism over prolonged engagement in the conflict without a specific goal or endgame.
Armed Services committee member Bill Nelson of Florida said he supported sending additional troops but said the US did not have much of a choice.
"The alternative -- if they were to leave -- it's going right back into the hands of the Taliban," Nelson told CNN's Wolf Blitzer on Tuesday, saying that he wanted to work toward a peace settlement.
Nelson said the situation in the country presented difficult problem for the US, and reminded him of the situation in Syria.
"I think the increase of some three to five thousand troops is a step in the right direction but be sober about the future," he added.
Senate Minority Whip Dick Durbin was skeptical the troops would make a difference.
"We have been engaged in this war for every 15 years and we are still struggling to determine how it can end favorably for the best interests of the United States and the Afghan people," he said on MSNBC Tuesday morning. "We have to ask ourselves a question: How long will this go on? How long will it be a battle, and when does it become a permanent occupation?"
Democratic Sen. Gary Peters, who sits on the homeland security and Armed Services committees, declined to weigh in until a plan was released.
"Over the last 16 years, the United States has spent trillions of dollars on the war in Afghanistan and lost over 2,000 American lives," Peters said. "I will be fully evaluating any plan that involves increasing the number of forces in Afghanistan to ensure that there is a clear strategy and end goal before the United States commits large numbers of additional troops."