Now we know China's 'bottom line'

This is how things get out of control.

The Global Times - a massive Chinese tabloid controlled by the ruling Communist Party - has ramped up its rhetoric over US intervention and Chinese action in the South China Sea.

"China mustn't tolerate rampant US violations of China's adjacent waters and the skies over those expanding islands,"said a recent Global Times editorial.

This, it said, would be "breach of China's bottom line."

For over a year China has been diligently building out the tops of island reefs in the South China Sea, reclaiming 2,000 acres of land and turning that land into military bases.

In April, satellite imagery showed that the Chinese military had built an airstrip big enough for military aircraft on one of those islands.

Freedom of navigation exercises

Sovereignty over the islands has become sacred in China, and when President Xi Jinping visited Washington last month, it was one issue where he and US President Obama did not see eye to eye.

China's "bottom line" may be in conflict with US objectives in the region. In June, Defense Secretary Ashton Carter called Chinese activity in the waters a violation of "international rules and norms that underscore the Asia-Pacific security architecture, and the regional consensus that favors diplomacy and opposes coercion."

The South China Sea is a crucial waterway through which more than half of the world's goods travel.

China's neighbors, many of which are US allies, have been dismayed by China's actions in the area.

The Philippines, Malaysia, Vietnam, Japan, and others in the region have expressed concern over China's designs on dominating the waters, as well as its build-out of islands into military bases.

Reports indicate that the US Navy plans to conduct "freedom of navigation exercises" in the South China Sea as a direct challenge to Chinese actions.

The Global Times published its editorial two days after Carter told a meeting with Australian defense officials that the US would continue to defy Chinese plans in the South China Sea.

He said: "Make no mistake, we will fly, sail and operate wherever international law permits ... We will do that in the time and place of our choosing."

Carter also signed a defense cooperation with Australia at the meeting.

Mike Nudelman/Business Insider

The tension has been building

This isn't the first time the Global Times has used this 'bottom line' rhetoric on the South China Sea. It used the same language back in June.

China was not on the defensive: "If the United States' bottom line is that China has to halt its activities, then a US-China war is inevitable in the South China Sea," the newspaper said.

"The intensity of the conflict will be higher than what people usually think of as 'friction.'"

But wait, there's more

Adding to that friction is the fact that China and US ally Japan have a dispute over a group of uninhabited islands in the sea - what the Japanese call the Senkaku Islands.

Earlier this month Japanese media reported that China had arrested a Japanese man on allegations of spying on nearby Nanji island. That island is about 186 miles (300 km) from the Senkakus and there have been reports that the Chinese are building a military base there.

On Friday, Chinese officials held a meeting in Beijing with the defense ministers of 10 nations in the region - the first of its kind. It's unclear what was discussed as media were not allowed to cover it.

"China desires cooperation and dialogue with ASEAN defense bodies to together safeguard regional peace and stability and join hands to create a good security environment," said Chinese Defense Minister Chang Wanquan.