Brisbane in lockdown as world powers arrive for G20 Russian President Vladimir Putin speaks with Australian Prime Minister Tony Abbott at APEC in Beijing. THE largest and most powerful political gathering in Australian history will get under way this week as world leaders mount a plan to boost the world economy. The planet's most influential people begin arriving in Brisbane today ahead of the weekend's G20 Leaders Summit, where multinational tax cheats, women in the workforce and private investment in infrastructure will be among topics for discussion. A ring of steel will encircle the city as an unprecedented peacetime security operation locks in to keep more than 7600 politicians, delegates and media safe. US President Barack Obama will bypass Brisbane Airport and arrive at Amberley RAAF base on board Air Force One on Saturday. He will then be flown in a helicopter into the Brisbane CBD. Russian President Vladimir Putin is also on the list, with his presence likely to stir anger over the 38 Australian deaths when MH17 was shot down over Ukraine in July. Mr Obama - who will be whisked around town in his armoured car flown in from the US and extensive security convoy - will give a key speech on US Leadership in the Asia Pacific region on Saturday. But Prime Minister Tony Abbott says the summit won't just be a "talkfest" and has dubbed it the "most important meeting ever held in Australia," with leaders representing 75 per cent of the world's population and 85 per cent of its GDP. At the close, each leader will commit to a "Brisbane Action Plan" to chart the way to two per cent economic growth over the next four years - a goal that would bring about millions of new jobs. Mr Abbott will push his infrastructure mantra in discussions, and wants more done to pull in private investment on roads, rail and ports as a way to grow economies. But he'll also argue for nations to do more to close the gender gap in the world's workforce - a topic that will be embraced by Japan Prime Minister Shinzo Abe, who has been a vocal proponent of more working women. And the sneaky tactic multinational companies like Google and Apple use to skirt international tax laws is also on Mr Abbott's agenda. About 6000 police from Queensland, interstate and New Zealand are patrolling the city and checkpoints .