From his office in Robertson Barracks, a sprawling base in the bush about 20 kilometres east of Darwin, the 18-year veteran of the Marine Corps carefully tiptoed around rumours the troop's presence was more than ''a training partnership'' and gave insights into what it was doing in the Top End. ''If we get down to brass tacks, the reason for us being here is to reinvigorate our relationship with the Australian Defence Force,'' he said. ''We have a history with Australia but in the recent past we have kind of got away from that - what with everything that is going on in the world. So we are here to kind of re-establish our partnership.'' When the marines arrived in early April for the first of their six-month rotations, the federal Defence Minister, Stephen Smith, justified their presence by saying: ''The world is moving in our direction. It is moving to the Asia-Pacific. ''It is not just the rise of China, it is the rise of China, the rise of India, the rise of the ASEAN economies combined, the emergence of Indonesia, not just as a regional influence but as a global influence,'' he said at a welcoming ceremony in Darwin. The decision triggered unease in China, according to reports in the Global Times, a state-run news organisation that suggested Australia should be cautious about allowing the US to use such bases to harm China.

But such high-level political concerns were quickly shrugged off by Colonel Senegar, a former Texas native. ''I wouldn't pretend to understand, or be able to speak intelligently on China's policy, but I see no reason for them to be concerned about our commitment to stabilisation of the region,'' he said. As his troops were out blasting targets and trying to avoid the heat during infantry training skills at the scrubby Kangaroo Flats training area, Colonel Senegar was emphasising their mission was unlikely to be combat related. ''We are going to go out and train but what has been historically coming up is humanitarian assistance and disaster relief and those are the two missions we are going to train for,'' he said. ''I don't remember the last time we did combat anywhere in this region, so that's not something we are really sitting around building plans for.''Reminded of the region's fondness for generating the odd, nasty little flashpoint, such as the near collapse of the government of East Timor in 2006 and the impending potentially eventful election campaign in Papua New Guinea, Colonel Senegar reiterated the humanitarian aid skills of his men but acknowledged that ''historically, as everyone knows, we do combat very well''. So far, his force stands at about 250 troops, composed of about 190 men from the ''Warchiefs'' or Fox Company as well as support and headquarters elements.

He said the 250-man rotation would probably remain at the same level for about two years but individuals in the US Marines and the Australian army were busily working out the best way to accommodate a deployment of about 2500. ''The Australian Defence Force will tell us what they can support,'' he said. Meanwhile the marines' impressions of Darwin are not exactly what they expected. ''They [the Marines] got an armchair tour and they get this vision of wild west from an American standpoint - a big open-air area with prairie dogs and tumbleweeds rolling around, but that's not what the Northern Territory is,'' he said. Colonel Senegar was cagey about how much liberty his men would have but he expected a high standard from them.

''Marines don't go out places looking like a bag of do-do. We try to uphold our professional commitment even in the way we look. No matter where we go, marines are considered ambassadors of the United States and we embrace that,'' he said. He said negotiations were under way to involve his men in outreach programs, including helping the indigenous community. As for the temptations of Darwin's nightlife and the lure of some of the city's notorious bars which have a reputation for a heavy drinking and violence, he said there were ways of keeping ''marines on task''. He confirmed his men were under curfew but the exact time it started, he said was ''internal information'' and not for publication. So far they have already impressed some of the locals.

A bar worker at the Palmerston Tavern, Stacey Janz, said a group of marines that turned up to have a drink at the hotel had been very low key. ''They even had a sober Bob,'' she said referring to a driving non-drinker who gets free soft drinks. But it's not likely to be plain sailing for the corps in Darwin. A local protest group, Basewatch, is planning a rally this month and has raised concerns about what is the legal status of the marines should they be involved in any crime. However, the marines' public affairs officer, Jeremy Croft, yesterday said the marines were subject to the uniform code of military justice and Australian law while on Australian soil.

Follow the National Times on Twitter: @NationalTimesAU Correction: The original version of this story had a caption describing Carlos Vasquez as a Lieutenant-Corporal. There is no such rank.

