DHAHRAN, SAUDI ARABIA, AUG. 21 -- Saudi warplanes have been playing an electronic "cat-and-mouse" game with Iraqi jets almost daily along their common border, but both sides have deliberately avoided any close encounters, according to a top Saudi air force commander.

Brig. Gen. Turki Bin Nasser, commander of the King Abdul-Aziz air base here, said that Saudi aircraft radar has been "locking onto" Iraqi jets flying near the Saudi border "almost every day" but that on every occasion they flew away.

Asked about reports that Iraq has moved Soviet-made Scud-B missiles into Kuwait, Turki said he was aware they had transferred some mobile missiles with a 300-mile range during the first week of the invasion. He said that with the presence of the U.S. Patriot antimissile system, Saudi Arabia now has the capability of downing the Scud missiles if they are fired. He acknowledged, however, that the Patriot has never been tried under battle conditions.

{In Washington, meanwhile, State Department spokesman Richard Boucher said that "we don't have any information to substantiate" reports about the movement of long-range Scud missiles into Kuwait. A U.S. military intelligence official said the reports apparently had misidentified Frog-7 missiles, shorter-range weapons routinely deployed with Iraqi troops, as Scuds.}

Turki's press conference here came as a senior Pentagon official traveling in the Persian Gulf region with Defense Secretary Richard B. Cheney said that the United States will upgrade Saudi Arabia's military capability, probably selling it advanced versions of the F-15 jet fighter and heavy tanks.

Turki said there is "always this cat-and-mouse thing" going on between planes of Saudi Arabia and Iraq. "We see them, we lock on and they turn and go." But he said warplanes from both nations were not flying close to the border, and he estimated the distance separating them at 30 to 40 miles.

The Iraqi pilots do not seem eager to challenge the Saudis, Turki said, and appear weak in their tactics. The eight-year Iran-Iraq war, he said, included no close-in air combat to give them experience.

Turki and his pilots expressed confidence in the combined U.S.-Saudi ability to establish quick air superiority over the Iraqi air force if war breaks out, and they expressed satisfaction with Saudi-American military cooperation so far.

Turki said the United States and Saudi Arabia have established a joint command to coordinate their military activities both inside the kingdom and over the Persian Gulf area -- the first public confirmation that the two are cooperating closely outside Saudi Arabia in the current crisis.

Establishment of a joint command underlines the extent of Saudi involvement in the expanding U.S.-Saudi defense network over the Arab side of the gulf. The general said that "living in an area like this," it is impossible to separate land, sea and air forces. He added, "It has to be well coordinated and under joint command."

He said the two forces also have established "the same rules of engagement" for dealing with any Iraqi challenge. He refused to outline the rules were but said that "all the forces here have the same rules of engagement" -- apparently referring to Egyptian, Moroccan and Syrian troops as well.

He said the U.S. and Saudi air forces were working well together because the Saudis have "exactly the same training" as the Americans, the same systems and "level of coordination."

American officers have expressed similar sentiments and said they have been pleased at the modern state of Saudi facilities, many of which are the best available technically anywhere in the Third World.

"These facilities are tremendous," said one American colonel. He noted that they were built to American specifications, many by American contractors under the supervision of the U.S. Army Corps of Engineers, over the last 30 years.

"They deliberately overbuilt these facilities for just such an occasion," he added.

The official accompanying Cheney said no specific agreements on new weaponry were reached during Cheney's visit with Saudi King Fahd and Defense Minister Prince Sultan, the Associated Press reported.

But the official said the need to upgrade the Saudi arsenal in the face of the Iraqi threat means the Bush administration will consider selling the Saudis high-powered F-15C and F-15D jet fighters as well as heavy tanks.

The official refused to confirm a report that the more sophisticated F-15E version of the fighter was also on the Saudis' "wish list," but he did not rule out such a sale.

Meanwhile, thousands of young Saudis lined up at military centers throughout the nation today in response to King Fahd's call for them to volunteer to protect the country, AP reported from Jiddah, quoting residents and officials.

"There has been a very positive and gratifying response to King Fahd's call," said Lt. Col. Ibrahim Baqi, commander of civil defense in Jiddah. In his area alone, he said, thousands of Saudis had rushed to sign up even before the king's appeal.