China and the United States have sailed aircraft carriers into contentious waters in the East and South China seas, the latest maritime contest between the strategic rivals at a time of heightened tensions in the region. Analysts say their naval presence in the Indo-Pacific at the same time highlights the risk of military conflict between the powers, as Beijing asserts its maritime claims in the region more aggressively and Washington focuses its defence strategy on countering China. It comes amid a deepening dispute between Beijing and Manila over the presence of Chinese vessels which the Philippines says are a maritime militia but China says are fishing boats in the Whitsun Reef in the South China Sea. Do you have questions about the biggest topics and trends from around the world? Get the answers with SCMP Knowledge, our new platform of curated content with explainers, FAQs, analyses and infographics brought to you by our award-winning team. The Philippine foreign ministry on Monday said Chinas claims that the boats were sheltering from bad weather were blatant falsehoods and clearly [a] false narrative of Chinas expansive and illegitimate claims in the West Philippine Sea. Manila also rejected Beijings assertion that the reef in the disputed Spratly Islands was a traditional Chinese fishing ground and again demanded the boats leave the area, in its exclusive economic zone, immediately. For every day of delay, the Republic of the Philippines will lodge a diplomatic protest, the statement said. The US, Japan and Indonesia also stepped up pressure on China over the dispute last week. On Sunday, a US aircraft carrier strike group led by the USS Theodore Roosevelt entered the South China Sea from the Strait of Malacca, according to the Beijing-based South China Sea Strategic Situation Probing Initiative, citing satellite data. It said the USS Mustin guided-missile destroyer was also operating in the East China Sea and edged close to Chinas Yangtze River on Saturday. Meanwhile, Chinese aircraft carrier the Liaoning passed through the Miyako Strait off southwestern Japan on Saturday, days after Chinas defence ministry urged Japan to stop all provocative moves over the contested Diaoyu Islands in the East China Sea, which Tokyo calls the Senkakus. The PLA Navy announced on social media on Monday night that the Liaoning was en route to conduct scheduled exercises near Taiwan, to test the effectiveness of troop training, and to improve the capacity to safeguard the countrys sovereignty, safety and development interests. Similar naval exercises would continue to be organised as planned, it said. Tokyo has repeatedly voiced concerns over Chinas new coastguard law that allows its quasi-military force to use weapons against foreign ships seen as illegally entering Chinese waters, and over the increased presence of Chinas coastguard in waters near the contested islands. Regional tensions have also been rising over Taiwan, where Beijing has in recent months ramped up grey zone warfare tactics against the democratic island it claims as its own. Ten Peoples Liberation Army fighter jets entered Taiwans southwest air defence identification zone on Monday, after Chinese Y-8 military aircraft flew near the island on Saturday and Sunday, Taiwans defence ministry said. The US also conducted a series of military exercises with its allies in the region last week, including with Japan in the East China Sea, with Australia in the eastern Pacific and with India in the Indian Ocean. Ben Schreer, a professor of strategic studies at Macquarie University in Sydney, said the US aircraft carriers passage in the South China Sea was meant to counter Beijings vast claims over the waters and signal to allies, such as the Philippines, that Washington was a reliable and capable treaty ally. India joins French-led naval exercise, revealing clues about Quads plans to contain China in Indo-Pacific At the same time, the Liaonings patrol in the East China Sea sought to demonstrate Beijings ambitions to use its own carrier strike group to defend what it saw as its core territorial interests, he said. Its a signal to Japan, the US and other powers in the region that the [Chinese navy] is gradually developing a carrier capability, though at present its nowhere near [achieving this], he said. Collin Koh, a research fellow from the S. Rajaratnam School of International Studies at Singapores Nanyang Technological University, said Washington was signalling its commitment to maintaining a credible military presence in the region to its allies and seeking to deter Beijing from any drastic actions amid the Whitsun Reef saga. The US also carried out naval exercises during a stand-off between China and Malaysia in the South China Sea last year, he said. Koh said the PLA Navys activities in the region, including its latest transit in the Miyako Strait, sought to underline its ability to operate against perceived American-led containment of Chinas maritime interests. The crowding of regional waters with rival maritime forces does create concerns about the risk of an accidental or inadvertent clash, he said. The onus will again be on both sides to professionally interact with each other. Xue Chen, a research fellow at the Shanghai Institutes for International Studies, echoed that view, saying there was a risk of human error in high-stress situations and noting the US air and naval forces had increased the frequency and scale of their activities in the East and South China seas and were going closer to Chinese territory. He said the USS Theodore Roosevelts presence in the South China Sea appeared to be a message to China but did not believe it was related to the Whitsun Reef dispute.More from South China Morning Post:South China Sea: will the Whitsun Reef dispute come between Beijing and Manila?South China Sea: Philippines says Whitsun Reef dispute shows China intends to occupy more featuresPhilippines repeats call for Chinese ships to leave Whitsun Reef This article China, US send warships into disputed waters as tensions rise over Whitsun Reef first appeared on South China Morning PostFor the latest news from the South China Morning Post download our mobile app. Copyright 2021.