Chief Warrant Officer Ralph Beacraft was talking about the several South Americans who have enlisted in the D.C. National Guard over the last [WORD ILLEGIBLE] years. "They make a hell of a good soldier," he said admiringly, "their attendance is excellent and they walk the line."

Beacraft said it was true that some had to be discharged when it was learned they had bought forged immigration papers, but even those were discharged honorably, "so I think they've got what they want."

What they want is a shortcut to American citizenship. Normally, it takes at least five years of continuous legal residence in the United States to qualify. But thanks to what Immigration and Naturalization Service officials see as a loophole in federal law, service of any length in the armed forces followed by an honorable discharge makes aliens instantly eligible for citizenship.

As a result of this legal quirk, said assistant INS Commissioner Andrew J. Carmichael," a problem is emerging around the country." Illegal aliens by the hundreds have been enlisting in the volunteer Army, Navy and especially the Marines, all with an eye towards quick citizenship.

"I'm not so sure," said Carmichael, "that there won't be much more of this in the future."

The quirk is the unanticipated result of a federal law passed in the 1960s by Congress in an effort to encourage service in the nation's armed forces by aliens.

Under that law, aliens who serve honorably in the armed forces of the United States during a period of hostilities immediately became eligible for U.S. citizenship. That exception to the normal route to citizenship was to end at least as far as Vietnam was concerned, when the president signed an executive order officially pronouncing the hostilities at an end.

But even though the Vietnam War has been over since 1975, no such executive order has been signed. As a result, aliens serving honorably in the nation's armed forces are still considered to have served during a period of "hostility."

"Undoubtedly, there have been enlistments of people who have entered the U.S. surreptitiously," said Carmichael. Others, he said, may have come in on tourist visas. "In some cases, they hoodwinked the recruiter and in some more serious cases they enlisted with the connivance of the recruiter," he said.

Since regulations of all the armed services require that recruits be either permanent residents or citizens of the United States, there must be some element of collusion, recruiter incompetence or fraud - either forged documents or a failure to check - in order for illegal immigrants to be able to enlist.

But to compound the complexity of the situation, there are many cases in which the military has been informed that a recruit has fraudulently enlisted and decides to keep him anyway.

A major part of the decision is often left to the man (or woman's) immediate superiors, and as Carmichael put it, "Oftentimes the local commander is more impressed by the man's performance than by how he got in."

Moreover, even if a recruit is discharged after only a few weeks of active duty, as long as his discharge is honorable (and usually it is) he is still eligible for immediate citizenship.

The Marines, for instance, are conducting a large-scale investigation as a result of the discovery last summer that 251 Panamanians had fraudulently enlisted in the New York City area with the apparent collusion of four recruiters. So far, according to a Marine spokesman, 153 of those enlistees have been completely processed.

While 73 of the Panamanians have been discharged (45 honorably, 29 with general, and four with other than honorable discharges), 75 - almost half - have been retained in the service.

A Navy spokesman said that since 1974 about 450 nonresident aliens have been discovered who were erroneously allowed to enlist in the Navy. "They have been retained," he said, "provided their conduct is satisfactory and they apply for naturalization as U.S. citizens." He said recruiting guidelines have been revised, however, to guard against enlistment of any more.

Army spokesman said they could not supply exact figures for the number of fraudulently enlisted foreign nationals, but there have definitely been problems. "All I know," said Lt. Col. Peter L. Clifford in the office of the deputy chief of personnel, "is that there is sufficient interest to know that we wanted to establish a policy that would make it extremely difficult for people coming into the Army with falsified documents."

If they are found to have enlisted fraudulently with the help of a recruiter, said Clifford, foreign nationals are dismissed with their service records wiped out, thus making them ineligible for citizenship. Those who fraudulently enlist on their own, however, may be discharged in the conventional manner.

A new Army policy now requires that all aliens who enlist be put on a delayed entry program without pay and without being sworn in for about 45 days, while a background check normally reserved for security clearances is run on them.

Immigration officials said that few of the illegal immigrants discovered thus far to have served or still be serving in the armed forces have actually been made U.S. MNN citizens. Naturalization processing is slow in any case and in these instances it has been further delayed pending completion of the various military investigations and the outcome of immigration court cases resulting from IMS opposition to the awarding of citizenship to an alien who has been honorably discharged. Eventually, however, it is expected that most of them will become citizens.

It is not clear why neither President Ford nor Carter have never signed an executive order that would officially end the Vietnam hostilities. INS officials said they have been asking the White House to sign such an order for three years.

Spokesmen at the White House, the National Security Council and the State Department said recently that they were not aware of the problem.

"As far as I know," said Elizabeth Verville in the State Department's legal section, "hostilities are not terminated by an executive order." She said she did not know, however, what might stand in the way of such an executive order being issued.

So, at least for now, as one immigration investigator summed up the situation, "We are at the mercy of the president."