BANGKOK — Sen. Tammy Duckworth, grilling President-elect Donald Trump’s selection for defense secretary over whether he had the “breadth and depth of knowledge” needed to navigator international negotiations, asked Pete Hegseth if could name one member of the Association of Southeast Asian Nations, describe what type of agreement the U.S. had with the countries and how many nations were in the bloc.

Hegseth responded at the heated Senate confirmation hearing that he couldn’t inform Duckworth the exact number of ASEAN nations, but that “I recognize we have allies in South Korea and Japan in AUKUS (a pact between Australia, the United Kingdom and the U.S.) with Australia.”

“None of those three countries are in ASEAN,” responded Duckworth, a Democrat from Illinois. “I recommend you do a little homework.”

ASEAN is made up of Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam. An 11th country, East Timor, is set to join soon.

Established in 1967, its objective is to promote regional economic and safety cooperation, leveraging a combined population of more than 650 million people with a GDP of more than $3 trillion.

Duckworth’s question came after Hegseth had noted the strategic importance of the Indo-Pacific, a region where China’s influence has been rapidly growing and Beijing has become increasingly assertive in pressing territorial claims.

ASEAN members Vietnam, the Philippines, Malaysia and Brunei are locked in maritime disputes with China over its claims of sovereignty over virtually all of the South China Sea, one of the globe’s most crucial waterways for shipping. Indonesia has also expressed concern about what it sees as Beijing’s encroachment on its exclusive economic zone.

The U.S. is treaty partners with ASEAN members Thailand and the Philippines, and Washington has sought to harness ASEAN’s regional influence as it seeks to counter Chinese influence and promote what the White House has called “a free and open region that is connected, prosperous, secure and resilient.”

President Joe Biden said ASEAN was “at the heart of my administration’s Indo-Pacific way” and hosted a conference of ASEAN leaders in Washington in 2022.

ASEAN also holds top-level meetings annually, this year in Malaysia, which holds the rotating chair of the throng.

Its defense meetings are typically attended by the U.S. defense secretary, and its foreign minister meetings by the U.S. secretary of state. The meetings culminate with an annual summit, which is regularly attended by the sitting U.S. president. Both Biden and Donald Trump have participated.

Despite some members’ territorial conflicts with China, many in the bloc have close relations with Beijing as well, and top-level Chinese officials also attend ASEAN meetings.

The U.S. in 2022 was elevated to the top-level “comprehensive strategic collaboration” with ASEAN — a largely symbolic position that put Washington on the same level with China, which was granted the distinction the year before.

ASEAN emphasizes noninterference and personal diplomacy, and its breadth of membership and partnerships makes it uniquely positioned as a forum to address major geopolitical issues.

Beyond China and the U.S., ASEAN has formal relationships with Russia, India, Australia, the European Union, Britain, Japan, South Korea and many others.

It hosts annual “ASEAN Plus Three” meetings with the leaders of China, South Korea and Japan, “ASEAN Plus Six” talks that add in the leaders of Australia, India and recent Zealand, and the East Asia summit, which includes the six plus Russia and the United States.

The ASEAN nations are also central to the Regional Comprehensive Economic collaboration, or RCEP, a free trade agreement that was signed in 2020, creating the largest trade bloc in history.

The 10 nations plus China, Japan, South Korea, Australia and recent Zealand account for more than 30% of the globe’s population and about 30% of global GDP. Conceived at ASEAN’s 2011 summit, the agreement includes commitments on trade in goods and services, investments and other areas.

Several ASEAN countries are also part of the Pacific rim trade pact known as the Comprehensive and Progressive Agreement for Trans-Pacific collaboration, or CPTPP, whose members also include Mexico, Canada, Australia, Britain, Chile, Peru and Japan, and whose economies make up more than 14% of global GDP.