A bipartisan group of influential U.S. senators has called on the government to draw up a strategy aimed at halting China’s “unilateral” acts to assert control over disputed islands in the South China Sea, including land reclamation projects.

The group, which includes Republican Sen. John McCain, head of the Armed Services Committee, and Republican Sen. Bob Corker, head of the Foreign Relations Committee, put the idea forward in a letter dated Thursday and addressed to Secretary of State John Kerry and Defense Secretary Ash Carter.

In the letter, the lawmakers noted “the alarming scope and pace of the land reclamation now being conducted” by China in the Spratly Island chain in the South China Sea. The chain is also claimed by countries including Malaysia, the Philippines and Vietnam.

Without a comprehensive strategy for addressing China’s broader policy and conduct to assert its sovereignty claims in the South China Sea and East China Sea, “long-standing interests of the United States, as well as our allies and partners, stand at considerable risk,” the letter said.

The two other senators are the top-ranking Democrats on the committees, Sens. Jack Reed and Bob Menendez.

“Unilateral efforts to change the status quo through force, intimidation, or coercion threaten the peace and stability that have benefited all the nations of the Indo-Pacific region,” the letter said.

China has been building various facilities to claim the islands in the South China Sea, including construction of an airstrip, despite objections by other countries.

Many claimants to a number of islands in the waters have been conducting land-reclamation projects but China has been outpacing them, U.S. officials said recently.

In the East China Sea, China claims the Japan-controlled Senkaku Islands, calling them Diaoyu. Beijing regularly dispatches its ships into Japanese territorial waters near the Senkakus.