Defense Secretary Robert Gates will use a weeklong Asia trip to reinforce the United States' commitment to the region, amid rocky relations with China, struggles with North Korea, and unease among the smaller allied nations.

Even as the United States sends humanitarian aid to cyclone-devastated Myanmar and the earthquake victims in China, Asian nations worry that the wars in Iraq and Afghanistan have made it difficult for the Pentagon to give the Pacific region the attention it requires.

"Everyone in the region recognizes that China is the huge new big player in all matters of Asian diplomacy, economics and military interactions," said Kurt Campbell, who heads the Center for a New American Security. "The elephant in the room is the anxiety that many Asians feel — that we are preoccupied away from Asia during a period of enormous consequence."

While Gates has indeed focused on the wars in Iraq and Afghanistan, this will be his fourth lengthy trip to Asia during his 17 months as Pentagon chief. It is his second appearance at the Shangri-la Dialogue, a prestigious Asia-Pacific conference on international security.

Gates arrived in Guam Friday, his first stop in the region. He is planning to take a tour of the military facilities here, including plans for a substantial increase in construction to house more than 8,000 additional Marines expected to relocate from Japan in 2014.

In recent years Gates' predecessor, Donald Rumsfeld, used the forum to air U.S. criticism of China's military buildup, and to call for greater transparency by the communist giant. Gates, however, has been more conciliatory.

Senior defense and diplomatic officials traveling with Gates Wednesday said that China is making slow progress in shedding more light on the massive military expansion. And they said the Pentagon took specific steps this year to make this meeting less confrontational. The officials spoke on condition of anonymity in advance of Gates' speech to the conference.

In the last several years, the U.S. has released a highly critical report on China right before the Shangri-la conference. This year, officials purposely put the report out on time in March, to avoid that face-off.

This trip also comes just as the U.S. is providing earthquake relief to the Chinese, including sophisticated satellite imagery of the area.

That cooperation is in contrast to several other, more confrontational episodes. In March the U.S. military mistakenly delivered fuses for long-range missiles to Taiwan, triggering a strong protest from Beijing. China opposes U.S. military relations with the small self-governing island that Beijing has claimed as its own since the sides split amid civil war in 1949.

The U.S. and China were also at odds over Beijing's shootdown of its failed weather satellite last year, which rained debris down into the Earth's atmosphere. Beijing then criticized the U.S. three months ago when the Pentagon shot down its own defunct satellite, amid concerns it could pose a danger if it fell in a populated area.

Guam which typifies America's plans to keep up a long and robust presence in the Asian Pacific.

The U.S. military plans to move the Marines and an equal number of their dependents to Guam from the southern Japanese island of Okinawa over the next decade. There are already about 7,000 Marines and their families here. The shift will leave about 10,000 Marines in Japan, said Pentagon press secretary Geoff Morrell.

That move had triggered a construction boom, including a new wharf, accommodations for additional ships, and an Army missile defense facility on Guam.

A senior defense official said the installation at Guam would give the United States a power base in a critical part of the world.

Guam's strategic location in the Pacific gives the U.S. a critical base from which to reach other countries in the region.

Campbell, who previously served as a senior Asia policy adviser at the Pentagon, said Gates has worked to repair some of Asia's anxieties stemming from the Rumsfeld era.

"He has managed to regain trust and confidence, and also present a much more welcome set of missions and messages to the broader world," Campbell said, predicting that Gates "will attempt to reknit the United States back into the fraying, little bit anxious Asian order. And that will be important."

Gates also plans to visit South Korea and Thailand later in his trip.