Recently, Chinese assertiveness was brought to the fore by its sparring with Japan over the Senkaku/Diaoyu islands in the East China Sea. In early September a conflagration of anti-Japanese protests and boycotts engulfed China after the Japanese government attempted to buy ownership of the disputed atolls from a Japanese businessman. The Chinese government responded forcibly, sending roughly 1,000 fishing vessels to the area, flanked by six frigates and several surveillance units.
However, this is not an isolated incident; such territorialism has long been visible in Beijing's regional strategy, particularly in its aggressive posture toward rival territorial claimants in the South China Sea dispute. Since the early 2000s, China has pursued an unwavering campaign to claim ownership of the sea's two disputed archipegalos – the Paracels and the Spratlys – that has embroiled it in countless diplomatic stalemates with the seven Southeast Asia states that also claim to hold sovereignty over the disputed reefs.
Combine this with its intense naval modernisation programme and alarm bells begin to ring. To some, it’s a harbinger of things to come; that China is increasingly working off a more imperial playbook. All across East Asia, from Tokyo to the Jakarta, the notion that Beijing is carving out its own Monroe Doctrine is taking on a new degree of salience.
To others, it can be argued that China is simply responding to American containment policies, especially at a time when Washington is embarking on a diplomatic and military “pivot” to East-Asia. 
Either way, the statistics are staggering. According to SIPRI, an independent research institute, China’s annual military budget has skyrocketed from $30bn in 2000 to $120bn in 2010 – a 400 per cent increase.
Worryingly for Japan and the seven nations embroiled in the South China Sea dispute (Vietnam, the Philippines, Indonesia, Malaysia, Taiwan and Brunei), much of this spending has gone on a kaleidoscope array of naval weaponry.
Last month, China unveiled the Liaoning – its first aircraft carrier – with five more reportedly in development. The People’s Liberation Army Navy (PLAN) has also stepped up its rate of submarine commissionings some 260 per cent between 2003 and 2012, whilst simultaneously transforming its previously outdated battleship force into a vast fleet of modern frigates, destroyers and amphibious vessels.
Such an extensive naval overhaul has afforded China the hardware it needs to buttress its claims and flex its muscle in the East and South China seas. More importantly, the wholesale development of “anti-access/area-denial” capabilities – or in layman's terms, land-based weaponry designed to destroy naval units – poses a profound threat to American interests in the region.
With weaponry as sophisticated as the anti-ship ballistic missile – a missile capable of destroying US aircraft carriers – alongside heavy investment in land-based maritime strike aircraft, the concern is that China is gearing its navy towards one that can deter US intervention when things get heavy in territorial disputes. Many pundits are warning of China establishing the near seas as a zone of exceptionalism in which it has carte blanche to pursue its ambitions unhindered; a domain in which even the world’s largest heavyweight, the US, has no jurisdiction.
The disputes also encompass a pronounced economic dimension: Oil. Chinese analysts estimate that the waters surrounding the Senkaku/Diaoyu islands may hold as much as 160 billion barrels of oil, and the South China Sea 213 billion – vastly outstripping Saudi Arabia’s reserves of 265 billion . And with China recently becoming a net oil importer, the seas’ hydrocarbon offerings become all the more tantalising.
The vying for sovereignty over the seas’ hydrocarbon-rich waters is at the heart of these territorial disputes and has drawn China into numerous naval standoffs in the past couple of years, the Senkaku/Diaoyu being the latest in a long list of confrontations.
The net result of such assertiveness has led to sharp deteriorations in Beijing's relations with the Association of Southeast Asian Nations (ASEAN) and almost all of its individual member states. Furthermore, China’s routine reference to the infamous “nine-dashed-line” – which covers 90 per cent of the sea’s waters and all its islands – as the basis for its claims has sparked a spiralling arms race in Southeast Asia. Virtually every state embroiled in the dispute has responded to China’s modernisation programme with its own, with overall ASEAN defense spending set to increase from $24.5bn in 2011 to $40bn by 2016, according to the Economist.
Whilst apocalyptic predictions  of China entering a momentous Pacific showdown with the US are entirely misplaced, if not ridiculous, China has developed an extensive near-seas capacity that provides Beijing the wherewithal to pursue its ambitions, whatever they may be.
Even though confrontations have so far been limited to standoffs between paramilitary ships and fishing vessels, China’s inexorable naval spending and the vehemence of its sovereignty claims undoubtedly cast a long shadow over its neighbours in the near seas.
And as the spectre of an expansionist China puts the wind in the sails of America’s “return” to East-Asia, Beijing may soon feel the pinch of its increasing regional isolation.
If it responds negatively to this, or if pushed , it will undoubtedly deal profound blows to the foundations of East-Asian stability, whilst putting the future of global security under thick clouds of uncertainty.
Watch this space.
Map source: NPR