Canberra - The Australian government says it will buy 12 new attack planes equipped with electronic warfare systems, as part of its new defence strategy.

The defence white paper also reaffirms Australia's alliance with the United States, describing it as the country's "most important relationship".

It describes China-US relations as the most important factor affecting Australia's geopolitics. It also says the government will aim to increase defence spending to 2% of GDP.

The paper was not due till 2014, but "significant developments in Australia's strategic circumstances... and the continuing adverse effects of the Global Financial Crisis" made it necessary to bring forward the white paper, the report said. Australia's last defence white paper was in 2009.

Australia would buy 12 EA-18G Growler electronic attack aircraft, the report said. The planes are equipped with radar-jamming equipment capable of knocking out electronic devices.

The government had previously announced that it would convert 12 of its 24 existing F/A-18F Super Hornet aircraft into Growlers. However, it decided to acquire 12 new Growlers instead to avoid taking any of the existing Super Hornets out of action, and "to assure Australia's air combat capability during the transition period to the Joint Strike Fighter".

Australia has long-term plans to acquire fifth-generation F-35A Joint Strike Fighter aircraft for its air defence, but is keen to maintain its air capabilities in the interim.

Australia also says it is committed to buying 12 new conventional submarines.

Australia did not believe it had to choose between alliance with the US and expanding ties with China, adding it welcomed China's rise, and the social and economic benefits it had brought.

However, Australia's Shadow Minister for Defence David Johnston questioned how the purchases outlined in the paper would be funded, and said the opposition Coalition would release its own defence white paper if it won the election. Australia's defence spending is currently around 1.56% of the economy.

Last year, Australia announced that there would be A$5.4bn ($5.5bn; £3.5bn) savings from the defence budget over four years.