WASHINGTON—The U.S. military is preparing to provide Kurdish forces in Syria with antitank weapons in their fight against Islamic State, U.S. officials said Monday, a move that would allow them to target armored Islamic State trucks used in suicide bombings but could also give them the ability to strike Turkish tanks operating in Syria.

Trump administration officials have been divided over whether to supply antitank weapons to the Kurdish force known as the YPG. The administration is trying to balance battlefield needs with objections from Turkey, which considers the Kurdish fighters to be a terrorist threat.

The Pentagon planning comes as President Recep Tayyip Erdogan prepares to meet President Donald Trump at the White House on Tuesday, when the issue of arming the YPG is expected to be a central point of discussion.

Last week, Mr. Trump signed off on plans to directly arm the YPG, a move meant to accelerate plans to uproot Islamic State from Raqqa, their de facto Syrian stronghold. Leaders in Ankara view the YPG as a branch of the regional Kurdish separatist force that has been fighting Turkey for decades. The U.S. views the YPG as a distinct fighting force and not a terrorist group.

In advance of his U.S. visit, Mr. Erdogan has said he still hopes to convince Mr. Trump to reverse course and stop plans to arm the YPG. But the U.S. military is already moving to supply the group with more firepower, including machine guns and other weapons, as well as ammunition.

Capt. Jeff Davis, a Pentagon spokesman, confirmed that the U.S. plans to supply the Kurdish fighters with antitank weapons. He declined to discuss details of the plan.

U.S. officials say the Pentagon has yet to make a final decision on the type of antitank weapons the U.S. will supply. To address Turkish objections, it is looking at providing the Kurdish forces with an unguided version of an antitank missile instead of the more sophisticated guided kinds, according to U.S. officials.

But even that has been the subject of debate. There are some in the administration who are worried about providing the YPG with any kind of antitank weapons, U.S. officials said.

Until now, the U.S. has restricted arms supplies to the Kurds as a way to assuage Turkish concerns that the weapons could be smuggled into Turkey and used against its own citizens and soldiers.

“That is a big concern for us,” one Turkish official said Monday of the plan to provide the YPG with antitank weapons.

Last summer, Kurdish fighters in Syria used an antitank weapon to destroy a Turkish tank, killing one soldier. The fighters likely seized the weapon on the battlefield. That attack, captured on video, heightened Turkish reservations about U.S. plans to arm the YPG.

The YPG is the largest force in the Syrian Democratic Forces, a coalition of about 50,000 Kurdish and Arab fighters who work with U.S. special operations forces.

Aaron Stein, a resident senior fellow at the Atlantic Council think tank, said providing antitank weapons to the YPG would fuel anger in Turkey, which launched airstrikes last month on the Kurdish fighters in Syria. Turkey has threatened to carry out more attacks against the YPG fighters, who often work side-by-side with U.S. forces in Syria.

“The SDF needs heavy weapons to assault Raqqa, but the provision of any of these weapons are certain to elicit a response from Turkey,” he said. “There is no threading this needle. The U.S. has simply chosen to elevate the [Islamic State] war plan over the Turkey relationship in the near term.”

—Gordon Lubold contributed to this article.