A spate of explosions hitting Red Sea cargo ships seems to bethe latest sign of Middle East rivals using unconventional means to press their causes. It is a sign of the times that by Monday - some 10 days after the explosions began - no firm indication had emerged of precisely what or who is causing them, and why.
The first explosions came at the north end of the Red Sea near Egypt, but in recent days ships have also been damaged near the southern end of the waterway.
The most widely heard speculation so far is that pro-Iranian militants may have mined areas of the Red Sea - an important shipping lane for oil and other cargo.
The Red Sea explosions coincide with a lull in the ''tanker war'' between Iran and Iraq in the Persian Gulf. They are seen by some Mideast analysts as a possible further spinoff of the nearly four-year-old Gulf war.
Among Mideast states with Red Sea coastlines are Egypt, Sudan, Saudi Arabia, and North Yemen.
The Egyptians are among major supporters of Iraq. The Gulf war aside, Egyptian authorities have been increasingly concerned in the post-Sadat era over the potential danger of Islamic extremism at home.
An index of Egypt's jitters over the explosions at its end of the Red Sea - in the Gulf of Suez - has been the generally closed-mouth response of Cairo officials to foreign reporters' queries on the issue.
On Monday, Egyptian Defense Minister Abdel Halim Abu-Ghazala did offer the most explicit official comment to date on the incidents. ''There are indications ,'' he said, that two countries were responsible for the explosions, but he did not name them.
Beyond potential political implications, the explosions cannot help causing concern in Egypt in light of the importance of Suez shipping revenues to the country's economy.
The suggestion that a pro-Iranian faction may be involved stems mostly from a claim of responsibility in London by a phone-caller saying he represented the ''Islamic Jihad'' organization.
This group - or phone-callers using the ''Jihad'' name - made similar claims following car-bomb attacks on United States Marines and Israeli forces in Lebanon.
The London phone-caller said nearly 200 mines had been planted in the Suez Canal and the Bab al Mandab strait - at the extreme northern and southern ends, respectively, of the Red Sea.
News agency reports from North Yemen, which borders the Bab al Mandab, cited diplomats as saying the most recent of the explosions seemed indeed to have been caused by ''low powered'' surface mines.
By late Sunday, at least nine vessels had reportedly been hit by explosions at either end of the Red Sea. Damage to most is reported to have been relatively minor.
But at least one ship, a Liberian-registered tanker, was reported Sunday to be sinking in international waters off the Yemeni coast.
One key problem for outside powers like the US in addressing the shift in the Mideast to unconventional tools of violence is to figure out precisely who are the perpetrators, much less how they can be best influenced one way or the other. This problem was particularly glaring in the case of the campaign of car-bomb attacks against US and Israeli targets in Lebanon.
The initial US response to the mysterious Red Sea explosions has been to dispatch mine experts to Cairo to join the Egyptians in efforts to find out precisely what is going on.
Reports from Washington also say American mine-sweeper helicopters have been placed on standby in Virginia for possible dispatch to the Red Sea area.