BANGKOK -- U.S. Secretary of State Antony Blinken begins his maiden tour of Southeast Asia on Monday, as Washington steps up its outreach to a region where China is also actively extending its influence.

Blinken has a slate of meetings with regional leaders lined up, during which he is expected to discuss relations with Beijing as well as other pressing issues such as Myanmar and the COVID-19 pandemic.

The secretary's trip starts in Indonesia, before he moves on to Malaysia on Tuesday and Thailand on Wednesday. He is scheduled to wrap up his tour on Thursday.

Southeast Asia is an increasingly important region for the U.S. It forms the geographic heart of President Joe Biden's strategy for a "free and open" Indo-Pacific -- pushing back against China's naval ambitions and militarization of the South China Sea. Association of Southeast Asian Nations members have also grown into key trade partners: Malaysia, Thailand and Indonesia are ranked 13th, 16th and 21st among exporters to the U.S., respectively, while they are the 23rd, 25th, and 32nd biggest importers from America, according to the U.S. Department of Commerce.

But U.S. relations with the region's governments are not always smooth. The visit closely follows the virtual Summit for Democracy the U.S. hosted last week. Of the three countries on Blinken's itinerary, Indonesia and Malaysia were invited but Thailand was not.

The visit also comes on the heels of the G-7 Foreign and Development Ministers' Meeting over the weekend, where the major industrialized countries sat at the same table with ASEAN counterparts for the first time. The G-7 members jointly raised concern over China's "coercive" activity in the South China Sea, where Beijing's vast claims overlap with waters claimed by several Southeast Asian states.

The G-7 and ASEAN partners shared concern over the waterway, too, and stressed their common interest in a free and open Indo-Pacific.

On his tour, Blinken is expected to gauge the three Southeast Asian countries' stances amid persistent diplomatic and economic tensions between the U.S. and China. Even as Beijing pressures the region over maritime territory, it has also courted ASEAN with vaccines and development assistance.

Myanmar will be another important topic. The G-7 and ASEAN jointly "expressed deep concern about developments" in the country, where the military has ruled with an iron fist since ousting Aung San Suu Kyi's democratically elected government in February. The State Department said Blinken would address the crisis in each country on his trip.

In Jakarta, Blinken is to meet with President Joko Widodo and several key government officials. He is also expected to visit a vaccine clinic run by an Islamic organization, according to Dan Kritenbrink, the U.S. assistant secretary of state for East Asia and Pacific affairs.

I Gede Ngurah Swajaya, director general for America and Europe at the Indonesian Foreign Ministry, said Blinken's visit marks "the start of high-level interactions" in the countries' "strategic partnership."

He cited Widodo's participation in U.S.-led forums since Biden took office -- including the democracy summit, the Global COVID-19 Summit in September and the Leaders' Summit on Climate in April -- as a sign of Jakarta's eagerness to rebuild ties with Washington that had deteriorated under Donald Trump.

Indonesia seeks to maintain an "independent and active" foreign policy but has found itself heavily relying on China for coronavirus vaccines and investment in the absence of other strong partners. Kritenbrink said Blinken will address this, saying he will discuss Biden's newly announced Indo-Pacific economic framework, in which the U.S. hopes to engage with regional partners on trade facilitation, building and securing supply chains, energy issues and environmental conservation.

On the COVID-19 front, Indonesia aims to become a manufacturing hub for vaccines to boost distribution to developing and low-income nations that still lack shots. Global vaccine equity -- among the topics Indonesia wants to push during its presidency of the Group of 20 that began this month -- is likely to come up for discussion while Blinken is there.

In Malaysia, Blinken is expected to meet Prime Minister Ismail Sabri Yaakob, shoring up relations with his new government formed in August.

Malaysian ministers and the U.S. secretary are set to discuss ways to further strengthen cooperation and explore new joint initiatives, a statement from the Foreign Ministry said. This includes ongoing active collaboration in trade and investment, digital and green economy, cybersecurity, defense, health, tourism, education and people-to-people ties.

"International and regional issues of common concerns will also be addressed," the ministry added.

Blinken's visit follows U.S. Commerce Secretary Gina Raimondo's recent stop in Malaysia, which focused on semiconductor cooperation.

In Thailand, Deputy Prime Minister and Foreign Minister Don Pramudwinai will welcome Blinken, with the secretary due to pay a courtesy call to Prime Minister Prayuth Chan-ocha.

While many countries try to avoid taking sides in the Washington-Beijing rivalry, Bangkok has appeared especially reluctant to do so, apparently hoping to reap investments from both. But as the 2022 chair of the Asia-Pacific Economic Cooperation forum, Bangkok is looking for a better relationship with the Biden White House.

Blinken will be the first secretary-level guest from the current administration. Vice President Kamala Harris and Secretary of Defense Lloyd Austin chose not to visit Thailand when they traveled through Asia earlier this year.

Thailand's domestic politics are a complicating factor, illustrated by its conspicuous absence from the democracy summit.

After leading a military coup and serving as junta leader for five years, Prayuth was elected prime minister in 2019 by a semi-democratic joint session of the lower and upper house, as the senators were hand-picked by the former junta without elections. The administration's authoritarian attitude toward anti-establishment protesters has also hurt its international image.

Thailand's dovish approach to the Myanmar military regime does not sit well with the U.S., either. Partly due to how the Prayuth government originated, it has been reluctant to apply pressure -- in stark contrast with Indonesia and Malaysia, which have vocally urged stronger action.

Additional reporting by Erwida Maulia in Jakarta and P Prem Kumar in Kuala Lumpur.