Australia\'s new military pact with the United States has increased tension over maritime security at a regional summit meeting in Bali. The meeting of the Association of South-East Asian Nations (ASEAN) will widen on Saturday into the East Asia Summit, which also takes in Australia, China, India, Japan, South Korea, New Zealand and, for the first time, the United States and Russia. But while existing priority areas of finance, education, environment, disaster management and health will feature in discussions, an increasingly tense dispute over sovereign rights in the South China Sea is set to steal much of the focus. Maritime security is not formally on the summit\'s agenda, but it is expected to be discussed in a retreat session under what has been called \'an exchange of ideas on regional and international issues\'. China and four ASEAN countries - Malaysia, the Philippines, Brunei and Vietnam - have staked territorial claims over the crucial sea lane, which handles more than a third of the world\'s seaborne trade and half its traffic in oil and gas. The expected \'exchange of ideas\' on the long-running dispute comes after the issue was fuelled earlier this week by the announcement that the US will use Australia as a base for an increased military presence in the Asia-Pacific region, viewed as a hedge against China\'s growing influence. Under the plan, announced in Canberra on Wednesday, up to 250 US Marines will train for six months at a time in the Northern Territory, just 800km from Indonesia, rising to a full 2500-strong Marine Air Ground Task Force by 2016. The US forces will bring ships, aircraft and vehicles. China has been relatively restrained in its response, but the plan has caused friction at the ASEAN summit with some members of the 10-nation bloc expressing annoyance at the timing of the announcement and its broader security implications. Malaysian Prime Minister Najib Razak said his country, which has strong economic ties with Beijing, did not back any development that would undermine regional security. \'Our position is we do not want any development that would undermine this region as a region of peace and stability nor anything that would increase tension in the region,\' he said. The Philippines, however, said an increased US military presence in the Asia-Pacific region would strengthen its hand against Beijing in the dispute over the South China Sea. Japan also welcomed the announcement. \'This is something we have ... been briefed from both the United States and Australia and we regard this as a demonstration of the United States\' commitment in the Asia-Pacific region,\' a spokesman for the Japanese foreign ministry said. \'This is something that will contribute to regional security.\' Prime Minister Julia Gillard, who was set to arrive in Bali on Friday afternoon, will probably move to downplay the significance of the military announcement when she meets other leaders on the sidelines of the East Asia Summit. It\'s understood Australian officials have already been attempting to make the case that the enhanced military ties with the US do not in any way complicate the South China Sea issue. Australia transports 60 per cent of its exports in the Asia-Pacific region across the sea. Ms Gillard is also expected to put forward a paper, co-sponsored by Indonesia, on disaster management in the region. The Asia-Pacific is considered the most disaster-prone region in the world, having been home to eight out of the 10 most deadliest disasters in 2009, and five out of the 10 most deadly disasters in 2010. It\'s hoped the proposal - which covers three broad areas including information sharing, overcoming bottlenecks and capacity building - will be endorsed by world leaders when the summit concludes on Saturday evening. Ms Gillard will stay in Bali for a bilateral meeting with Indonesian president Susilo Bambang Yudhoyono on Sunday. A range of issues will be discussed, and will probably include the case of the 14-year-old Australian boy facing the possibility of a three-month prison sentence in Bali after he was allegedly caught in possession of a small amount of marijuana. It\'s likely, however, that Dr Yudhoyono will want to discuss Australia\'s new military pact with the United States, on which Indonesia was briefed just two days before it was announced.