CHINA'S insistence that American and other foreign ships and aircraft must seek its permission to carry out military activities in a vast swathe of water off its coast has been a source of bitter contention and occasional conflict with the United States.
So the official confirmation earlier this month, at the Shangri-La Dialogue in Singapore on Asia-Pacific security, that the Chinese armed forces have themselves been recently doing what they had for years tried to forbid the US from doing has raised some intriguing questions.
Beijing has long asserted that it has the right to regulate foreign military operations in and over its claimed Exclusive Economic Zone (EEZ). This stretches 370km from the outer edge of its territorial sea.
The territorial sea is measured from baselines close to China's coast and around its islands out to a distance of just 22km.
Beijing has argued that military activities in its claimed EEZ, except for routine navigation and overflight, pose a threat to its national security and are inconsistent with the peaceful-purpose provisions of the United Nations Convention on the Law of the Sea (Unclos).
When the Unclos treaty came into force in 1994, creating the new category of EEZ jurisdiction, nearly 38 per cent of the world's oceans that had been considered high seas beyond national control suddenly became subject to coastal state authority for resource exploitation and environmental protection.
Beyond this, the US and most other countries took the view that in EEZ waters and the airspace above, foreign ships and aircraft conducting peacetime military activities had the same rights in the EEZ as they had in and above the high seas.
In other words, the full range of intelligence gathering and operational activity needed for the safe and secure operation of US' and other countries' surface ships, submarines and aircraft engaged in legal military activities in foreign EEZs remained legal.
This was seen as vital for a global power like the US which depends on freedom of navigation and overflight to move its military ships and aircraft unhindered around the world. It was particularly critical in Asian waters, where a series of semi-enclosed seas - among them the South and East China seas, the Yellow Sea and the Sea of Japan - were completely or largely covered by the new EEZs.
China was not the only country that contested the majority view about limited coastal state authority in EEZs. But in Asia, only China and North Korea went to the extent of trying to disrupt US military activities in their claimed EEZs. China did so multiple times between 2001 and 2009.
Among the most serious incidents was the harassment in April 2001 by a Chinese Air Force jet of a US EP-3 electronic intelligence spy plane operating in China's EEZ near Hainan island in the South China Sea.
A mid-air collision between the two aircraft resulted in the death of the Chinese pilot, the landing of a badly damaged EP-3 on Hainan, and an international crisis that was aggravated when China refused to return the plane and release the crew.
However, as China continues to enlarge its navy and extend its reach into the Pacific and Indian oceans, Chinese surface ships, submarines and aircraft are themselves reported to be operating in foreign EEZs in the region with increasing frequency. These include those of Japan and India.
So perhaps it was only a matter of time before the contradiction emerged, as it did during the Shangri-La Dialogue on June1. Senior Colonel Zhou Bo informed a maritime security panel that the Chinese navy had "sort of reciprocated America's reconnaissance in our EEZ by sending our ships to America's EEZ for reconnaissance".
Col Zhou did not say where the activity took place, whether Chinese submarines or surface vessels were involved, or what exactly they were doing.
But in May, the Pentagon reported to Congress that the Chinese navy was conducting military activities in the EEZs of other nations without their permission. It said that the US had observed over the past year several instances of Chinese naval activities in the EEZs around Guam, a US island territory and military hub in the western Pacific, and Hawaii, in the central Pacific.
The Pentagon report added that while the US considered Chinese naval activities in America's EEZ to be lawful, "the activity undercuts China's decades-old position that similar foreign military activities in China's EEZ are unlawful".
Does Beijing now recognise this as well? And will it end attempts to disrupt and halt US military activities in China's EEZ?
If so, it would significantly lower tension with the US armed forces in the region. It would also diminish the impression that China is intent on carving out an exclusive sphere of influence for itself in North-east and South- east Asian waters.
It might also persuade other Asian countries that seek to restrict foreign military activities in their EEZs, particularly bigger powers with expanding navies like India, that the time has come to drop the policy.
Influential Chinese analysts have been thinking along these lines for some time now. One of them, Professor Shen Dingli, director of the Centre for American Studies at Fudan University, wrote in The Diplomat a couple of years ago that China and the US needed to improve cooperation.
He suggested that the US respect the legitimate rights of China and other countries to access the high seas. "China, for its part, may be obliged to reinterpret its use of its EEZs in accordance with Unclos," he wrote.
However, Beijing may be engaged in a more cynical exercise.
China shows no sign of being prepared to settle its conflicting claims with Japan and some South-east Asian countries to sovereignty and other forms of jurisdiction over islands and maritime areas in the East and South China seas, by submitting them to UN-linked courts and tribunals for adjudication or arbitration.
Instead, it may be aiming to make the US even more reluctant to intervene in these maritime disputes in opposition to China because vital American interests in freedom of military operations in Asian seas are no longer at stake.
The writer is a visiting senior research fellow at the Institute of Southeast Asian Studies.