The Trump administration has taken steps toward leaving a nearly three-decade-old agreement designed to reduce the risk of war between Russia and the West by allowing both sides to conduct reconnaissance flights over one another’s territories, U.S. officials said.

The withdrawal would mark a further step toward dismantling the post-Cold War arms-control framework, already buffeted by the demise of the Intermediate-range Nuclear Forces Treaty and the uncertain fate awaiting the New START accord on U.S. and Russian long-range nuclear arms, which expires in 2021.

President Trump has signed a document signaling his intent to withdraw the U.S. from the 1992 Open Skies Treaty, two U.S. officials said.

The White House wouldn’t respond to questions about whether the administration has decided to pull out of the treaty. One of the officials said discussions were continuing.

“Anything is possible with this president,” the official said.