With the White House still discussing military possibilities" and American forces in striking distance of Iraq, the United Nations (U.N.) Security Council yesterday passed a U.S.-sponsored resolution to impose heavy economic sanctions against the Iraqis for their invasion of Kuwait.

The Iraqis, however, seemed determined to fight such measures yesterday, rounding up some 300 foreigners and warning Western nations that they should consider "their interests and citizens in Kuwait" before attempting any military reprisals.

The U.N. measure, passed unanimously by the 15-member Council except for abstentions by Cuba and Yemen, bans all imports of commodities from Iraq or Kuwait. The sanctions--only the third to be imposed by the Council in its 45-year history--came five days after Iraq invaded Kuwait and overthrew that country's government, after about two weeks of threats that it would do so if Kuwait did not curtail its oil production.

The vote also follows decisions by other world powers to impose similar sanctions on the Iraqis. The United States, Japan and the European Community have already voted to boycott all Iraqi and Kuwaiti imports, while both the Soviet Union and China announced last week that they will halt arms shipments to Iraq.

Although the sanctions are legally binding, the United Nations has no formal mechanism to enforce them, other than calling for military action by member nations. President Bush, however, vowed yesterday that "these sanctions will be enforced--whatever it takes."

And while U.N. sanctions have been flouted in the past, experts here praised the decision as an important first step toward making the Iraqis back down.

"Economic sanctions supported by major powers ... shouldn't be underestimated," said Robert Keohane, an international relations scholar who chairs Harvard's Government Department. "That's the first step, and its impact shouldn't be underestimated."

Although that impact could be devastating--Iraq's economy is almost completely dependent on oil exports--the White House said yesterday that it was still discussing"military possibilities" to stop Iraqi aggression.

Of particular concern is the danger that Iraqposes to Saudi Arabia, and, to a lesser extent,Turkey. Those two nations control the pipelinesthrough which Iraq exports its oil, and as ofyesterday, Iraqi troops were still massed alongthe Saudi border.

In denouncing the "naked Iraqi aggression" onSunday, Bush hinted strongly that military actionwould follow any Iraqi moves against Saudi Arabia.Yesterday, Defense Secretary Richard Cheney metwith Saudi leaders to discuss possible militaryarrangements in that country, while Secretary ofState James A. Baker III prepared to visit Turkey.

"The defense of Saudi Arabia is paramount,"White House spokesperson Marlin Fitzwater saidyesterday. It is, he added, "clearly in thenational interest to stop [Iraqi President] SaddamHussein."

Officials will not confirm exactly whatmilitary options Bush is considering, but lastnight Pentagon sources said that the aircraftcarrier Independence and an accompanyingtask force were within striking distance of Iraqisoil.

Should Iraq move against the Saudis, scholarssay, the U.S. would be justified in takingmilitary action. But experts warned that just asthe U.S. worked hard to coordinate multinationalsanctions, it should try to encouragemultinational military responses, lest otherMiddle East nations resent a unilateral Americanintrusion into their affairs.

"Here we have a ready made situation for U.N.action," Keohane said. He added that "it would bea bold Iraqi President who would kill U.S. andSoviet soldiers."

Yet the Iraqis may have already taken othersteps to deter a direct military response.

In a statement carried by the Iraqi News Agencyon Sunday, the Iraqi-installed military governmentof Kuwait warned other nations not to take"punishing measures" against either it or Iraq.The provisional government said that countries"have to remember they have interests and citizensin Kuwait."

So yesterday, the Iraqis rounded up more than300 American and British citizens working inKuwait, and transported them to Baghded. TheIraqis made no demands and U.S. officials saidthey were unsure whether the Westerners were beingheld hostage.

In the Iraqi capital of Baghdad, PresidentSaddam summoned Joseph Wilson, the U.S. charged'affaires, and "warned against any act that mightendanger the region's peace and security," theofficial Iraqi news agency reported.

Iraqi army commander Saadi Mehdi Saleh wasquoted by the Al-Iraq newspaper as sayingAmericans "should understand that the people ofthe great leader Saddam Hussein cannot befrightened."AP Wire PhotoBritish Prime Minister Margaret Thatcherdiscusses the Middle East situation with reportersin the White House Rose Garden just after meetingwith President Bush in the Oval Office.