Canberra, Australia (CNN) -- The United States announced an agreement with Australia Wednesday that will expand military cooperation between the long-time allies and boost America's presence in the region.
The agreement was revealed during a joint news conference between U.S. President Barack Obama and Australian Prime Minister Julia Gillard in the nation's capital, Canberra.
Obama is on a two-day trip to Australia, his first visit as commander-in-chief.
"I am very pleased that we are able to make these announcements here together on Australian soil," Obama said. "Because of these initiatives that are the result of our countries working very closely together as partners, we are going to be in a position to more effectively strengthen the security of both of our nations and this region."
While U.S. officials cited the need to respond to regional natural disasters as a reason for the agreement, concern over China's military expansion is widely acknowledged as a driving factor.
"What we look at is how does our general force posture allow us to protect U.S. interests, protect our allies, and ... secure the region broadly," Deputy National Security Adviser Ben Rhodes told reporters traveling with the president. "China is obviously a piece of the Asia Pacific region, an emerging power."
Rhodes later added that the deal is "part of the U.S. sending a signal that we're going to be present, that we're going to continue to play the role of underpinning security in this part of the region. Part of that context is a rising China."
Analysts note that the deal sends a message to China in a less confrontational way than building up bases closer to Chinese shores.
"The Chinese can squawk about it," said Patrick Cronin, senior director of the Asia-Pacific Security Program at the Center for a New American Security. "But it's not like having an aircraft carrier in the Yellow Sea."
Obama himself, however, insisted during his news conference that "the notion that we fear China is mistaken."
The president's Australian visit -- postponed twice in 2009 and 2010 due to an oil spill in the Gulf of Mexico and other domestic political considerations -- highlights a changing balance of power in the Pacific as China expands its military reach and the United States works to reduce its military footprint in Japan.
Obama's Australian visit comes on the heels of last weekend's 19-nation Asia-Pacific Economic Cooperation summit, which highlighted the need for new measures supporting job growth. During the Hawaiian summit, Obama stressed the importance of the Pacific to global economic security, and he pushed China to do more to help strengthen the world economy.
After wrapping up his visit to Australia, Obama will conclude his Pacific trip with a stop in Indonesia -- a country he spent several years living in during his childhood.
CNN's Charley Keyes and Alan Silverleib contributed to this report.