SINGAPORE—The United States on Saturday called for an “immediate and lasting halt” to reclamation works in disputed waters in the South China Sea, saying Beijing’s behavior in the area was “out of step” with international norms.

“First, we want a peaceful resolution of all disputes. To that end, there should be an immediate and lasting halt to land reclamation by all claimants,” US Defense Secretary Ashton Carter told a high-level security conference in Singapore.

“We also oppose any further militarization of disputed features,” he said, stressing that US forces would continue entering what he called international waters and airspace in the tense region.