Russia's President Vladimir Putin (R) meets with Australia's Prime Minister Tony Abbott during the Asia Pacific Economic Cooperation (APEC) Summit in Beijing
Russia's President Vladimir Putin (R) meets with Australia's Prime Minister Tony Abbott during the Asia Pacific Economic Cooperation (APEC) Summit in Beijing, November 11, 2014. REUTERS/Press service of the p

U.S. naval vessels have monitored a Russian naval force as it heads to Australia in a show of military force as Russian President Vladmir Putin attends the G20 summit in Brisbane. American surface warships are believed to be tracking the movements of the Russian vessels.

The U.S. and the Australian Defence Force are in close contact over the progress of the Russian warships at sea, according to The Australian. When the Russians headed south more than a week ago, Australia sent the Royal Australian Navy frigates HMAS Paramatta and HMAS Stuart and RAAF's P3 Orion maritime patrol aircraft to watch their movements.

International media reports have suggested that a U.S. submarine is observing the ships. The presence of Russian ships near the Australian coast has sparked speculation that a fifth vessel, a nuclear submarine, is part of the group.

Reports said it was common for a Russian taskforce away from the country to be accompanied by a nuclear submarine which would serve as a scout ahead of the flotilla. The arrival of Russian ships may be part of the government's international display of strength. In recent weeks, Russian bomber planes have been spotted heading towards NATO airspace in Europe. They were also detected in the U.S. and over Japan's territorial waters.

Meanwhile, the arrival of Russian ships has only added to the tension between Mr Putin and Mr Abbott who has earlier said he will "shirtfront" the Russian president to get answers over the MH17 tragedy. The passenger Malaysia Airlines aircraft was believed to be shot down from the sky by pro-Russian separatists. The crash has killed 298 people, including 38 Australian residents and citizens.

Mr Abbott told media it was not unusual for Russia to send naval vessels during important international events, but he found the presence of Russian warships strange in Australian waters. The prime minister believes Russia has become more assertive of its military strength in the Pacific. He also mentioned the country's assertiveness in Ukraine. Mr Abbott has assured that Australia continues to monitor the Russian ships as they approach.

Speaking at a press conference ahead of the G20, Mr Abbott said he had pointed out to Mr Putin that Russia would be more appealing if it would transform into a "superpower for peace, freedom and prosperity" instead of "recreating" the power of the old Soviet Union.