For years, Americans have been complaining that their country's foreign policy is weak and confused.

It made little difference who was in the White House. We criticized Republican and Democratic presidents with even-handed vigor.

The invasion of our embassy in Tehran and the events that followed give us a good opportunity to review what has been wrong with our foreign policy -- and what has been right about it.

If the Soviet embassy had been taken over, there would have been Soviet tanks in the streets of Tehran just as quickly as planes could fly them in. Iran would have become another Soviet province. Iranian diplomats and civilians who happened to be in the U.S.S.R. on the day of the attack would have been rounded up, arrested and helds as countervailing hostages.

If the Israeli embassy had been taken over, there would have been a retaliatory air strike within a few hours. If that didn't get the message across, a commando rescue mission would have explained matters more clearly and gotten the hostages out.

In both instances, lives would have been lost, but a familiar warning would have been written out in blood again: "Don't mess with me."

The American government hasn't used that kind of big stick policy for decades. The world's troublemakers know it, and they take calculated risks based on our known reluctance to get tough. We are kept busy reacting to the crisis they generate.

Although I learn much about public attitudes from mail sent by readers, I would be unwilling to guess whether most Americans would have supported an instantaneously tough response to the attack on our embassy.

If a referendum had been held, would a majority have favored military action, even at the risk of setting off a war with the Soviets? Or would a majority have backed the course President Carter chose?

We'll never know. But this much I can tell you: The thing that is most responsible for making our foreign policy seem ineffective is our reluctance to put military muscle behind diplomatic negotiations.

However, it is not clear whether in the long run this helps us or hurts us.

It hurts when our restraint gives others the impression we're weak. It helps when people "vote with their feet" as they flee from the Soviet Union and try to find havens in other lands, especially ours.

When people begin trying to escape from the United States to go live in Russia, I'll know there's something wrong with our policies. But while the tide is running in the opposite direction, it seems obvious that in spite of our errors, we must be doing a few things right.

After the Iranians defied international law by making hostages of our diplomats, we could have seized their diplomats and put knives to their throats. But we chose a seemingly incongrous way to "retaliate." We provided their people with massive police protection and eventually told them to go home.

It seems so illogical. They refuse to let our people go home, but we let their people go scot-free.

Has this policy of restraint been wise or unwise? It might be informative to poll the thousands of Iranian students who have poured into this country, legally and illegally, and ask them two questions: "Why have so many of you chosen to come here? Why have so few of our people chosen to move to Iran?" Would we discover that some of the policies and attitudes that make us appear weak also make us appear attractive as a homeland?

While we're waiting for the answers, Congress ought to award a medal to the State Department official who insulted the Iranian charge is still sputtering with rage when he gets back to Tehran, perhaps the Head Beard over there will begin to understand that there are limits to human patience -- even to Mr. Nice Guy's. GETTING STONED IN PUBLIC

For 14 consecutive years, many Maryland legislators have been trying to enact a bill that would require truckers to put a tarp over "loose" loads carried in open vehicles. For 14 consecutive years, other Maryland legislators have managed to foil the will of the majority. It happened again in this year's session.

So gravel trucks will continue to fly along Maryland highways shedding stones and pebbles. Roadways will remain littered with thousands of dangerous missiles that will eventually be flung backward into the windshields of following vehicles.

It is time Maryland's voters got as tough with their political hacks as President Carter has gotten with Iran. Voters should ask themselves: "How can the truckers' interest always win out over the public's interest when there are a thousand times as many people not in the trucking business as there are in it? What's the payoff?"