DHAHRAN, SAUDI ARABIA, SEPT. 13 -- Iraqi forces in Kuwait have maintained a formidable offensive capability, even though they have spent much of the past five weeks digging into defensive positions, according to the U.S. military's top commander.

"We have learned not just to look at their disposition on the ground," said Colin L. Powell, chairman of the Joint Chiefs of Staff. "They have a robust defense . . . but they have the capability of becoming offensive." Powell spoke to reporters today after his first visit to U.S. troops in Saudi Arabia since the military buildup here began five weeks ago.

Powell said "there have been some glitches" that have slowed the movement of forces and equipment to the Middle East. He said the sealift operaton has been hampered by breakdowns of fast sealift vessels and delays in deploying the naval ready reserve fleet.

However, the four-star Army general said he is "very satisfied with he amount of force" now in the region. Military officials say about 143,000 troops are now in the Middle East, but Powell would describe the figure only as "well, well over 100,000."

During a whirlind tour of Air Force F-15 flight lines, tank units in the desert and Marines stationed near a major port, the most frequently asked questions by the troops here was, "When are we leaving?"

The repeated response from Powell: "I can't answer that question yet." The chairman added, "We have no desire {for} a permanent presence." Powell also said he is reluctant to provide special financial and other benefits to troops participating in Operation Desert Shield when thousands of other U.S. troops are deployed in austere conditions around the globe.

Powell said policy-makers are considering "a full range" of efforts to assist troops assigned to the Middle East, including free postage. In addition, the military is considering rotating units out of Saudi Arabia "as soon as it's practical."

Correspondent Steve Coll added from Manama, Bahrain:

U.S. Navy and Coast Guard forces patrolling Middle East waters are boarding three to four commercial ships daily to search for Iraq-bound cargo prohibited by United Nations sanctions, a senior Coast Guard officer said today.

The number of boardings, between 30 and 40, mainly in the Red Sea, has increased markedly in recent days, according to Capt. Paul J. Prokop, the senior Coast Guard commander participating in the U.S.-led multinational blockade against Iraq.

Senior naval officers directing the blockade also have discussed extending their operations to check on Iranian tankers that might be selling oil abroad for Iraq's benefit, a Navy spokesman said. While the discussions have not yet led to expanded rules of engagement for U.S. warships in the region, they indicate that U.S. officials are concerned about whether Iran intends to help Iraq dodge United Nations sanctions.

Two commercial ships determined to be carrying nonmilitary cargo for Iraq have been turned away from the Jordanian port of Aqaba this week, including one vessel that was diverted today, Navy officials said. Neither of the intercepted ships was registered in Iraq and neither resisted orders to change course, they said.