Bangkok, Thailand — Trade is likely to overshadow politics in Secretary of State George Shultz's talks with America's Southeast Asian allies this week. Kampuchea, often the main subject of any talks between the United States and the six-member Association of Southeast Asian Nations (ASEAN), may figure less prominently this year. Instead, Western protectionism - an increasing source of irritation to ASEAN - is likely to be one of the main items on the agenda.
Most of the talking will be done in Jakarta, where foreign ministers of ASEAN nations (Indonesia, Malaysia, the Philippines, Singapore, Thailand, and Brunei) are holding their annual meeting July 9 and 10. This will be followed by dialogue with ASEAN's six main noncommunist political and trading partners, the US, Japan, Australia, New Zealand, the European Community, and Canada.
One of the main obstacles to development, the Southeast Asian nations say, is the West's imposition of import restrictions on Asian goods and commodities.
''The US and other Western countries espouse the principle of free trade, but they put quotas on us,'' an ASEAN official said. ''We buy US machinery, but when we use it to produce goods, we can't sell them in the US.''
''The Reagan administration keeps talking about the US economic upturn - perhaps because it's election year. We'll probably ask Shultz how the upturn will help our access to US markets.''
ASEAN and five of its noncommunist allies will have a special meeting to discuss possible cooperation among nations bordering the Pacific Ocean. (The odd partner out is the European Community.)
Indonesian Foreign Minister Mochtar Kusumaatmadja reportedly intends to unveil a plan for economic and cultural cooperation among Pacific Rim countries.
Other participants at the meeting, Western as well as ASEAN, say they will be happy to examine the plan but view this year's Pacific nations' dialogue more as an experiment. They are waiting to see whether this year's discussion will generate the enthusiasm required for a closer, longer look at the idea.
The notion of pan-Pacific cooperation has been floating around now since at least the 1960s. But it has been hampered by, among other things, the number of eligible countries and their glaring ideological disparities. According to one count, there are at least 51 countries qualifying for membership, including the Soviet Union, the US, and China.
Kampuchea will still figure in the Jakarta talks. The US will probably repeat its support for ASEAN's position, and its determination to follow the association's lead on the subject.
ASEAN countries tend to find this only slightly less irritating than the US position on trade. They would like the US to provide open, direct, military aid to the noncommunist members of the anti-Vietnamese Coalition Government of Democratic Kampuchea (CGDK).
At the moment, the US claims to be providing only indirect humanitarian aid through international relief agencies. There are, however, strong indications that it has been giving direct, covert, and financial aid to members of the CGDK for some time now.
In their own discussion on Kampuchea, ASEAN states are likely to stress continuity. They will respond to last week's declaration of the foreign ministers from Vietnam, the Vietnamese-backed government in Kampuchea, and Laos, which called again for a broad dialogue on regional issues, including Kampuchea.
The response is likely to be negative. ASEAN doubts that Vietnam is ready to negotiate; Thailand has already dismissed the proposal as nothing new.
Moreover, ASEAN feels things on the battlefield in Kampuchea are beginning to go their way. They say the CGDK forces were more successful this year than in previous years in parrying the Vietnamese operations against them during the recently ended dry season.
They also claim that the three CGDK factions, which have in the past often functioned as separate and mutually suspicious entities, are beginning to work together. The most recent indication of this, ASEAN officials say, was last week's meeting in Peking of the three CGDK leaders, Prince Norodom Sihanouk, Son Sann, and the Khmer Rouge's Khieu Samphan. The meeting was reportedly held at the initiative of Sihanouk and was intended to coordinate plans for the diplomatic offensive that culminates in this fall's vote on Kampuchea's credentials at the United Nations General Assembly.
And even the usually skeptical Chinese seem to be more favorably inclined toward the noncommunist CGDK forces. A senior Chinese diplomat recently completed a secret 12-day visit to coalition camps along the Thai-Kampuchean border. He returned impressed by the improvement in morale and fighting capability of the Sihanouk's and Son Sann's forces and may have endorsed the requests the two groups made for more weapons.
Given this generally optimistic picture, ASEAN seems content to look to the long term.
ASEAN officials say that their ministers' final delcaration will probably remind Vietnam of some of the benefits of a negotiated settlement of the Kampuchea question - reconstruction aid, for example.
But they do not expect an immediate reaction.
''Everybody in ASEAN feels that Vietnam is not ready to talk,'' said one official. ''We just have to outwait them, set the Kampuchea question aside, and get on with our economic development.''