With President Donald Trump’s new effort to rein in U.S. military deployments abroad now extending to Afghanistan, Democrats who have spent years urging an end to the American mission there see glimmers of hope and a chance at rare cooperation with the White House.

On the surface, it seems like an ideal opportunity for bipartisanship. As they take over the House of Representatives next month, top Democrats want to highlight the 17-year conflict in Afghanistan, showing progressives that the party acknowledges their anti-war fervor and signaling to voters more broadly that the party acknowledges the need for change amid public anxiety about the United States’ standing in the world. As for the president, an aversion to idealistic missions like the U.S. bid to turn Afghanistan into a stable democracy is one of his few consistent political opinions.

But Democratic lawmakers and aides also expressed a strong degree of trepidation. The standard Trump-related chaos and poor planning ― not to mention a resurgent Taliban ― could lead to ugly results over there during or after the monthslong process of bringing home 7,000 troops. Supporters of a drawdown risk the kind of embarrassment that could seriously set back efforts for a less hawkish approach to national security. Right now, Democrats have almost no way to ensure that doesn’t happen.

“Trump’s instincts to withdraw are correct,” said Rep. Ro Khanna (D-Calif.) in a statement issued after HuffPost requested a comment on the policy shift. “But the tactical implementation matters.”

An aide to Sen. Elizabeth Warren (D-Mass.), a likely Democratic presidential candidate who called just last month to bring American forces back from Afghanistan, said the senator was awaiting details of Trump’s plan.

Other prominent Democrats associated with the campaign against the ongoing U.S. presence in Afghanistan ― Reps. Barbara Lee (D-Calif.) and Jim McGovern (D-Mass.) and Sen. Jeff Merkley (D-Ore.) ― didn’t immediately respond to HuffPost’s requests for comment.

The Afghanistan move is trickier to analyze than Trump’s other big foreign policy step earlier this week ― his decision to end the U.S. presence in Syria ― because of how little the administration is publicly sharing on the Afghanistan shift. On Twitter, the president has indicated that he wants to let other countries take responsibility for the remaining fight against Islamic State holdouts in Syria. But his decision about a significantly larger number of troops in Afghanistan ― three times more, in fact ― has so far been communicated largely by anonymous officials talking to outlets like The Wall Street Journal, which first broke the news.

With less detail about what Trump plans in Afghanistan, it’s also harder for skeptics of the president to highlight how he could mismanage a policy they would otherwise support. On Syria, by contrast, Democrats from Lee to Sen. Chris Murphy (D-Conn.) have said they agree with Trump on not over-extending the U.S. military but worry about the consequences of his proposal for a rapid pullout, noting for instance that Kurdish fighters who fought alongside Americans could suddenly feel abandoned and vulnerable.

Still, lawmakers see one big red flag in the new Afghanistan policy. So far there’s no explanation for how the troop reduction fits with what’s supposed to be the top priority of the U.S. over there ― the effort to craft a sustainable peace deal between the country’s elected, Western-backed government and the Taliban militants that America has been fighting since 2001 over their ties to al Qaeda.

“We must have a robust, multilateral, and inclusive diplomatic initiative to encourage national reconciliation, local peacebuilding efforts, and the engagement of regional actors such as Pakistan, Iran, Russia, China, and India,” Khanna said. “The State Department needs a strategy to secure an inclusive and lasting peace settlement, a plan for the full withdrawal of U.S. troops from the country, and sustained support for nonmilitary peacebuilding solutions to secure any political settlement reached by the Afghan people.”

With U.S. officials currently engaged in shuttle diplomacy with the Taliban and other power players in the neighborhood, a lot depends on how the drawdown decision is interpreted. The insurgents could see it as a goodwill gesture ― or a sign that they should hold off on agreeing to anything and wait to make more battlefield gains once the American presence dwindles.

That kind of heightened tension is exactly what peace groups don’t want to see. Congress will likely want a timeline on how the withdrawal will work and what kind of future military action Trump expects to take in Afghanistan, Khanna said. Without a strategy going forward, the president could end up simply having to reverse his decision or to authorize new kinds of military operations.

It doesn’t help that Kabul’s capabilities remain weak despite years of U.S. funding and training, with the government now controlling only slightly more than half the country, according to U.S. officials, or that Trump has crafted his shift without much consultation with experts or America’s allies in the anti-Taliban fight, according to The Wall Street Journal.

One senior U.S. official told the newspaper that the president’s decision is primarily about not wanting to be involved in wars. Just as Trump made clear on Syria that he expects others will still be fighting against the remnants of ISIS, it appears that he cares less about whether peace in Afghanistan is actually on the horizon and more about having nothing to do with the place. That’s an approach that could mean more bloodshed for Afghans and others on the ground, and one day the cost of more American lives.

Paul Blumenthal contributed reporting.