The international community was swift to condemn the launch by North Korea on Sunday morning of what Pyongyang claims was a rocket to put a satellite into orbit. South Korea, which firmly believes the launch was a test of a long-range ballistic missile, was quick to declare that it was opening discussions with the United States about deploying state-of-the-art defensive missile systems.

The decision prompted anger in China, which swiftly summoned the South Korean ambassador to Beijing to express its opposition, and the concern now is that countries in the region - already tense - may be stumbling into a tit-for-tat escalation of military spending.

Seoul has been debating the introduction of the Terminal High-Altitude Area Defense (THAAD) system for at least two years, but has always deferred a final decision out of consideration for China. The two neighbors have grown closer in recent years - in terms of trade, economics and even on security issues - and South Korea has had no desire to jeopardize that burgeoning relationship.

North Korea's ongoing belligerence, however, means that Seoul realizes that it needs to prioritize security of its own territory and citizens. And in a pointed aside, Seoul called on Beijing to stop attempting to "influence" its national security policies.

'Good reason to be worried'

"South Korea has good reason to be worried about the actions of North Korea, and seeking talks with the US on the deployment of THAAD seems to me a completely reasonable response," Jun Okumura, a visiting scholar at the Meiji Institute for Global Affairs, told DW.

Seoul's concern is of "rogue attacks" from North Korea, said Okumura, but Beijing's worry is the deployment of advanced US weapons systems close to its borders, and what it senses as South Korea backing away from the burgeoning friendship and returning to the embrace of Washington, which has guaranteed its security since 1945 and, most notably, during the 1950-53 Korean War.

"China wants to regain its position of the natural hegemony of east and Southeast Asia, so in the same way as both North and South Korea are acting in what they see as their national interests, Beijing is doing the same," Okumura said.

Chinese defense spending has increased in double-digits annually for the last 30 years, Okumura pointed out. And while that may not be a sprint for military superiority in the region, it could be considered spending over the term of a marathon.

Ignoring UN sanctions

And while South Korea might not have perceived China as a threat to its territory, the same cannot be said about a regime in North Korea today that consistently refuses to adhere to United Nations sanctions imposed after previous nuclear and long-range missile tests. Such is the disdain with which Pyongyang holds the rest of the international community.

There are concerns that North Korea is planning a new underground nuclear test just to show that it will not be cowed. That attitude, in turn, has led to calls in some sections of South Korean society for the nation to develop and deploy its own nuclear deterrent.

On January 28, after Pyongyang had conducted the test of what it claims was a thermonuclear device, the South Korean newspaper Chosun Ilbo ran an editorial headline of "South Koreans must discuss acquiring nuclear arms."

Pointing out that China was doing little to rein in the North Korean regime and that Pyongyang responds to slaps on its wrist by the UN by becoming even more belligerent, the editorial said that as soon as the North completes development of its nuclear weapons and the missiles to deliver them, "the military balance on the peninsula will tilt dangerously."

Nuclear option discussions

"Seoul now faces a real need for public discussion of the development of its own nuclear weapons," the newspaper added. "If the public wants the country to arm itself with nuclear weapons, the government will simply have to scrap a joint declaration from 1991 to denuclearize the Korean Peninsula and initiate talks with the US to obtain the right to enrich uranium and reprocess its own spent nuclear fuel rods."

Neither the US nor China want such a scenario to come to pass, and both are also keeping a wary eye on the security landscape in Japan, where Prime Minister Shinzo Abe is using the aggressive territorial demands of China and the unpredictability of North Korea to win support for his proposals to rewrite parts of the Constitution that forbid Japan from using force in international disputes.

There have been voices in Japan, too, calling for the nation to at least consider a nuclear capability. "There is talk in both South Korea and Japan about each nation exercising their rights to have the nuclear option, but we're not at the point yet where that would be acceptable to the majority of people. I do not think that North Korea's recent actions will be the game-changer on that," said Professor Jeff Kingston, director of Asian Studies at the Japan campus of Temple University.

"Having said that, this saber-rattling by the North is going to go a long way to helping Abe promote revisions to the constitution, for example," the professor added. "The actions of North Korea are constantly upping the ante and while I wouldn't say we are seeing an arms race at the moment, Pyongyang is making it tough to tone the situation down," he said.

"Ultimately, North Korea wants leverage without the situation reaching the point of conflict," he said. "So the rest of the players in the region find themselves in a stalemate on how best to deal with the regime - and that plays into Pyongyang's hands because it gives them further time to develop improved military capabilities."