July 25 marked the beginning of the largest U.S. military exercises in South East Asia since the onset of the Korean War in 1950. The USS George Washington aircraft carrier strike group is performing war games in conjunction with the South Korean Navy.

Tensions are steadily rising across the region as the United States and South Korea present a united front against the growing threat posed by North Korea.

On March 26 a South Korean warship, the Cheonan, was inexplicably sunk killing 46 sailors. Investigators have found undeniable evidence that the ship was sunk by a North Korean torpedo. The United Nations Security Council (UNSC) condemned the incident, but due to pressure from China, the UNSC did not specifically accuse North Korea as the assailant.

The incident has put U.S.-China relations in a precarious position.

Fearing a destabilizing flood of North Korean refugees, China continues to support the isolated regime of Kim Jung-Il.  

Historically an act of aggression like the sinking of the Cheonan would have required explicit authorization from China. Yet the North Korean regime appears to be unraveling and erratic in its behavior.

The declining health of Kim Jung-Il is splitting the regime across reformists and military hardliners jockeying position.

The unpredictability of the regime leaves the U.S. at an impasse with 28,500 troops stationed at the demilitarized zone that separates the North from the South.

U.S.-China relations appeared to be improving given China’s instrumental role in bringing North Korea to the negotiating table in a series of 6-party talks aimed at ending its nuclear program.

Following six years of fruitless negotiation, North Korea pulled out of the talks in April of 2009. The increasingly erratic behavior of the North including its failed test of a nuclear warhead has strained the rapprochement of US and China.

Military ties between the U.S. and China, seen as key to regional stability, have been completely severed.

Defense Secretary Robert Gates has repeatedly said that China’s growing military build up and ambition to deploy its navy farther out into the world could cause security concerns and an arms race unless stronger relations can be cultivated.

Congressional leaders have faulted the Pentagon for failing to deliver a report on the status of the Chinese military to include in budget discussions.

Without this report and no clear indication from the Chinese leadership seeking greater cooperation, Secretary Gates will be forced to recommend a larger defense budget to meet the emerging Chinese threat.

The inability or unwillingness of China to check North Korean aggression particularly in the sinking of the Cheonan only serves to reinforce the military exercises being undertaken by the United States.

For the first time the Air Force has deployed the F-22 air superiority jet fighter to South Korea. The most technologically advanced fighter in existence, the F-22 has the ability to remain undetected in North Korea airspace and serves as a powerful reminder to China of the overwhelming advantage the U.S. military maintains in resources and technology.

The presence of the F-22 comes on the heels of reports that the U.S. Navy has also deployed four of its recently converted ballistic missile nuclear submarines to the region carrying hundreds of Tomahawk cruise missiles.

These submarines together with the F-22 and the USS George Washington aircraft carrier highlight the growing and alarming arms race between the U.S. and China.

The U.S. and China need to find common ground and work together in terms of security and world trade.

The international community--especially the developing world--cannot afford a 21 Century cold war.

North Korea and regional hegemony will remain pivotal issues for both countries. As the U.S. seeks to solidify the defenses of its democratic allies and maintain its influence, it will increasingly come into conflict with Chinese ambitions and its continued foster-ship of North Korea.

The American-South Korean military exercises mark what has become a regular precedent in U.S.-China relations.

The two countries must not resort to military bluster and expressions of force. Diplomatic re-engagement is vital to the pragmatic success of both nations going forward.

A new era in U.S. foreign policy should usher in a dawn of mutual security and dialogue among nations rather than drag the angst of past hostilities into the regional environ.

Reach columnist Brian Tenenbaum here.