As Washington and Beijing spar in a dangerous game of one-upmanship to determine who will control the strategically critical waterways of the South China Sea, some defense observers and regional analysts worry that the U.S. effort will prove an exercise in futility in the long term against the full weight of China’s growing military and economic prowess.

China’s strategy of slowly but methodically building up military installations in the Spratly Islands, the Scarborough Shoal, the Fiery Cross Reef and other strategic points within the sea, coupled with Beijing’s increasingly assertive territorial claims, has elevated tensions in Washington and unsettled U.S. allies in the region.

The White House and Pentagon have taken solace in the fact that China’s military ambitions have been tempered by its commercial interests, according to a Defense Department review of the country’s strategic footprint in the Asia-Pacific region.

“China still seeks to avoid direct and explicit conflict with the United States,” Pentagon analysts concluded in a report issued in April. “China’s leaders understand that instability or conflict would jeopardize the peaceful external environment that has enabled China’s economic development.”

But some warn that Pentagon strategists are making a serious miscalculation of China’s military goals and capabilities, as well as of American preparedness to curb those ambitions, by relying on the belief that the country’s economic needs will prove a durable bulwark against military action in Asia.

“We believed that American aid to a fragile China whose leaders thought like us would help China become a democratic and peaceful power without ambitions of regional or even global dominance,” said Michael Pillsbury, director of the Hudson Institute’s Center for Chinese Strategy. “Every one of the assumptions behind that belief was wrong — dangerously so.”

China has taken a number of steps “to send messages to the rest of the world” about its willingness to defend its interests, said Dean Cheng, senior research fellow at The Heritage Foundation’s Asian Studies Center. Among those messages: that Beijing is “inflexible” in defending its South China Sea claims and that it has embarked on “major military reforms which will make it a much more capable opponent.”

Even the Defense Department analysts noted that China is “focused on developing the capabilities they deem necessary to deter or defeat adversary power projection and counter third-party — including U.S. — intervention during a crisis or conflict,” the April report states.

Over the long term, “China’s military modernization is producing capabilities that have the potential to reduce core U.S. military technological advantages,” according to the Pentagon.

The trends are not favorable: A Center for Strategic and International Studies report this year mandated by Congress concluded that China will have so many aircraft carriers in the area within 15 years that the sea will be “virtually a Chinese lake, as the Caribbean or the Gulf of Mexico is for the United States today.”

This cat-and-mouse game between China and the U.S. and its allies boiled over recently when Beijing scrambled a team of fighter jets to track a U.S. warship as it sailed by a disputed patch of land in the heart of the South China Sea.

While such incidents in the past raised the hackles of military leaders in Beijing and Washington, most were resolved quietly through diplomatic channels. But the Chinese response to the U.S. ship’s traverse through the Fiery Cross was particularly sharp.

That response could signal China’s determination to dominate the open seas as its shoreline becomes increasingly backed by military force, the head of U.S. Pacific Command told Congress.

China’s military is actively “changing the operational landscape in the South China Sea,” Adm. Harry B. Harris Jr., commander of the U.S. Pacific Command, warned members of the Senate Armed Services Committee last year.

After decades of the U.S. military serving as the decisive power and security arbiter in the region, China in recent years has pushed a different message: It’s time for Washington to butt out. Ahead of broad-ranging talks this week between top U.S. and Chinese diplomats and financial officials, the lead Chinese negotiator told reporters over the weekend that Washington should let countries bordering the South China Sea work out their conflicts on their own.

“In fact, the United States is not a claimant in the South China Sea dispute, and it has said it takes no position on territorial disputes,” said Vice Foreign Minister Zheng Zeguang. “So we hope the U.S. can stick to its promise and not choose sides, and instead base its stance on the rights and wrongs of the case.”

Raising the stakes

Chinese commanders in May ordered a team of fighter jets into the skies above the Fiery Cross Reef near the Spratly Islands after the USS William P. Lawrence conducted a “freedom of navigation operation” close to the reef, also claimed by Taiwan, Vietnam and the Philippines.

The U.S. ship’s course near the Fiery Cross, which Beijing maintains falls within Chinese territorial waters, was also part of a suspected surveillance mission to observe the 10,000-foot runway newly constructed on the reef, Chinese officials said.

“The action by the U.S. threatens China’s sovereignty and security, endangers the safety of people and facilities on the reef and harms regional peace and stability,” Chinese Foreign Ministry spokesman Lu Kang told the state-run Xinhua News Agency at the time. China “will continue to take measures to safeguard our sovereignty and security.”

The U.S. warship’s mission was a “simple act of provocation” designed to further inflame regional rivalries and embolden U.S. allies to take action against China, he said.

The Pentagon defended the action, noting that the American warship was operating in international waters in compliance with global rules of the sea.

Obama administration officials have tried to downplay the drama of the Navy missions through the South China Sea by insisting that they are simply passing through widely recognized international waters.

Secretary of State John F. Kerry rejected outright China’s claim that the operation was intended to provoke an armed response from the American warship.

“This is not a pointed strategy calculated to do anything except keep a regular process of freedom of navigation operations underway,” he said.

But the practice of American warships trolling the South China Sea in various shows of force was a lackluster strategy to check Beijing militarily.

“The United States continues to send mixed messages through its [Freedom of Navigation Operations] program, which was designed to maintain freedom of the seas,” said The Heritage Foundation’s Mr. Cheng.

“In reality, the United States has still avoided actually conducting military activities of any sort off the Chinese man-made islands, despite there being no legal reason not to do so.”

Some warn that the U.S. cannot match China if it seeks short-term fixes while Beijing plays a longer game. As long as China avoids a direct provocation that leads to war, the scales will continue to tip in its favor.

The South China Sea islands — and the suspected energy riches under its seabed — may not “really [be] the objective of Chinese expansion,” analyst Phil Reynolds wrote in a recent survey of the South China Sea standoff.

“Rather, the goal of China’s grand strategy may be to successfully challenge the United States in the eyes of the world. If China is correct, any actual conflict with the United States will not end in an all-out war. Intense pressure from the international community will quickly lead to a negotiated settlement. This is a win for China.”