The United States, facing a rising China but a tighter budget, expects to station several combat ships in Singapore and may step up deployments to the Philippines and Thailand, a naval officer said.

The United States has been increasingly vocal about defending freedom of navigation in the South China Sea, where tensions over territorial disputes between Beijing and Southeast Asian nations have been on the rise.

In an academic article forecasting the shape of the US Navy in 2025, Admiral Jonathan Greenert, chief of naval operations, wrote that "we will station several of our newest littoral combat ships" in Singapore.

Greenert said that the United States may also step up the periodic deployment of aircraft such as the P-8A Poseidon -- which is being developed to track submarines -- to regional treaty allies the Philippines and Thailand.

"The Navy will need innovative approaches to staying forward around the world to address growing concerns about freedom of the seas while being judicious with our resources," he wrote in the December issue of the US Naval Institute's Proceedings.

"Because we will probably not be able to sustain the financial and diplomatic cost of new main operating bases abroad, the fleet of 2025 will rely more on host-nation ports and other facilities where our ships, aircraft, and crews can refuel, rest, resupply and repair while deployed," he wrote.

The naval officer did not directly mention China, as part of the usual policy by US President Barack Obama's administration to publicly seek a more cooperative relationship with the growing Asian power.

But the United States has laid bare its concerns about China. Obama last month announced that the United States would post up to 2,500 Marines in the northern Australian city of Darwin by 2016-17, a move criticized by Beijing.

The United States also has some 70,000 troops stationed in Japan and South Korea under longstanding alliances and has offered assistance to the Philippines which launched its newest warship on Wednesday.

Singapore is also a long-standing partner of the United States. The US military already operates a small post in the city-state that assists in logistics and exercises for forces in Southeast Asia.

In the article, Greenert described the Gulf monarchy of Bahrain as a model. The US Fifth Fleet is based on the small island which is strategically close to Afghanistan, Iraq and Iran.

"In 2025 the Navy will operate from a larger number of partner nations such as Bahrain to more affordably maintain our forward posture around the world," he wrote.

The United States spent some $700 billion on its military in the past year, far more than any other country, and many lawmakers accept the need for cuts as the Iraq and Afghan operations wind down.

The Obama administration has identified Asia -- full of fast-growing economies and with a still emerging security order -- as the key priority for the United States.

Obama, Secretary of State Hillary Clinton and Defense Secretary Leon Panetta all traveled to Asia in recent months to hammer home the message that the United States will not leave the region despite economic woes at home.

"As the United States puts our fiscal house in order, we are reducing our spending," Obama said in his speech in Darwin.

But he added: "Here is what this region must know. As we end today's wars, I have directed my national security team to make our presence and missions in the Asia-Pacific a top priority."

Naval power, critical to the rise of the United States and earlier Britain as global powers, is expected to remain critical in the 21st century.

China has developed its first aircraft carrier, which has undergone two sea trials this year. An image of the 300-meter (990-foot) refitted former Soviet carrier was captured by US-based company DigitalGlobe Inc.