The United States military intervention in Grenada is facing guerrilla ''pockets of resistance,'' which eventually could cause the US problems more political than military in nature.
At present, the US-led invasion and occupation of Grenada seems to enjoy the support not only of much of the English-speaking Caribbean but also, as far as can be ascertained, of most Grenadians.
However, according to several well-placed Caribbean sources, both popular and government sentiment in the region tends to favor a relatively rapid withdrawal of US troops from the island. It also favors the replacement of US troops by Commonwealth forces, which could help take heat out of the issue internationally by removing it from the arena of East-West confrontation.
Most of the governments in the region want US troops to finish ''mopping-up'' operations. There have been no negative reactions to statements by the US military spokesman in Barbados, Vice Adm. Joseph Metcalf III, that foresaw American troops remaining in Grenada for at least one month.
However, there is an underlying anxiety that, as one prominent observer of the Caribbean scene put it, ''The US and its military have been unleashed and once they are unleashed it's hard to put them back into the bottle.''
These anxieties have not been allayed by the scale of US intervention. According to press reports, there are 5,000 marines on Grenada and 10,000 waiting offshore. This, according to a US source, is ''overkill'' - a response far out of proportion to existing military threats and giving an unnecessarily high profile to the US presence. Some reports said there was US aerial bombing.
This source says that if current resistance does develop into short-term guerrilla warfare, the US must attempt to eliminate the core of that resistance and then transfer its military responsibilities on the island into other hands as quickly as possible. The source is, however, is afraid this willnot happen because ''the military tends to go in with more - and stay in with more - than the situation really demands.''
''In this case,'' he feels, ''the political price of that could be high.''
He said it likely that President Reagan will rely on military estimates of when to withdraw and that such estimates would push for a longer rather than shorter occupation. In any case, large amounts of US aid would be needed.
The fight against the resistance forces in Grenada present none of the dangers of a land war in Asia or anti-guerrilla warfare in Central America, and could provide the military with easy victories to make up for their frustrations in other parts of the world, this source said.
There were other concerns about an unnecessarily high US profile in the area.
According to US government sources, the US profile will be further heightened in the region by the opening soon of a US embassy in Grenada. Charles A. Gillespie, deputy assistant secretary of state for Latin American affairs, is presently shuttling between Barbados and Grenada making arrangements for the embassy opening.
The ''pockets of resistance'' are largely from scattered snipers and bands of Cubans and Grenadians in the island's mountainous interior. As of Saturday night , a US official said some 200 to 300 Cubans had not been captured and were continuing resistance in the hills. Some 800 had been captured, along with Grenada's former Deputy Prime Minister Bernard Coard, who reportedly led the coup that toppled Prime Minister Maurice Bishop. By Sunday, 16 US soldiers were killed, with 77 wounded, and 3 missing.
Also resisting were an unspecified number of former Grenadian Army and Popular Militia members, many of whom shed their uniforms when the invasion began. Although the US military seemed to be focusing on the Cubans, Grenadian sources in Barbados described some of the Grenadian military as very well trained (in Cuba and East Germany) and highly motivated.
It is possible that the present resistance could develop into some short-term guerrilla struggle, sources say. The mountainous, terrain of Grenada is suited to this form of warfare. But because of the small size of the island and the resistance's lack of popular support, the possibility of a long-term Salvadorean-style guerrilla warfare can practically be ruled out. There have been accounts of Grenadian soldiers burying arms and supplies but reports from the island also stress that the local population has been very cooperative in exposing the presence of these arms caches to US forces.
Whatever government forms in Grenada, the latest crisis will have a wider regional impact. One source says that the region is at a crossroads.
The US has intervened in an area of small island-republics that are not politically, economically, or militarily viable as individual entities. The Reagan administration and the countries of the area have a choice:
* The region could embark upon an arms race with each small island buying weapons and expanding its forces.
* Or these small, poor islands could pool their resources, creating greater economic cooperation and eventually some form of confederation - a confederation that might not only further economic development but also provide for a joint security force whose decentralized authority might reduce the likelihood of coups.
From London, contributor Alexander MacLeod reports:
Nations of the British Commonwealth are mounting an urgent effort to replace US troops on Grenada with their own multinational force.
The initiative was being coordinated by Shridath Ramphal, secretary-general of the Commonwealth, a grouping of more than 40 former British colonies. Ramphal , a Guyanan diplomat, hopes military units from Caribbean states as well as Australia, New Zealand, and Canada will form the basis of the peace force.
Britain, still angry at the way President Reagan handled the Grenada crisis, is expected to give provide logistic support to put the force in place. It may stop short of contributing troops.
Prime Minister Margaret Thatcher's aides made it clear that she is still furious about the invasion. There were also unmistakable signs of resentment in Buckingham Palace. Queen Elizabeth is head of state of Grenada and has her own representative on the island, Governor General Sir Paul Scoon. Sir Paul, US officials claim, had appealed to Washington for help rather than Britain.
Formation of a provisional government, in the Commonwealth secretary-general's view, should run parallel to arrival of a multinational Commonwealth force to replace Americans.
It seems probable that the US will steadily give way to units from Grenada's Commonwealth neighbors in the Caribbean. Troops from Jamaica and Barbados, as well as smaller countries of the area, will be reinforced.
Ramphal's plan is that in a week or two Canadian, Australian, and New Zealand units should be flown in. Britain may provide ships and aircraft.