If Osama bin Laden was behind the attacks on the US, it proves his terrorist organisation has improved beyond recognition. If Islamic militants are found guilty of last Tuesday's attacks on New York and Washington, the world community will be compelled to re-examine its entire approach to what has been vaguely termed "international terrorism". Neither strategic military strikes nor a protracted campaign to capture or kill militants can eliminate the threat they pose.
From the evidence gathered by US agencies, it appears the men who hijacked four civilian aircraft and crashed three into the World Trade Centre and the Pentagon were disciples of the Saudi-born dissident, Osama bin Laden, although not necessarily members of his al-Qa'ida group.
If this is true, then his followers have made a qualitative leap in performance; from detonating crude car bombs at poorly guarded US embassies in Africa to flying state-of-the-art jetliners into prime targets in the continental US, from being low-tech to hi-tech operatives in a war being waged by Islamist militants against the sole superpower.
The leap would be a giant one, accomplished by medium-term strategic planning, finely tuned logistics, strict security and absolute dedication. None of these elements was evident in previous attacks blamed on bin Laden. According to the US Federal Bureau of Investigation, 50 terrorists may have been involved, 40 of whom have been identified. At least 18 took part in the hijackings; a trained pilot was in each of the four aircraft.
Twenty-seven of the suspects had flight training in Florida and California and may have been acquainted before the operation. The knife-wielders are said to have belonged to four autonomous cells which had no contact before the operation. These men may have been activated by a pre-arranged sign or code word.
They travelled great distances to carry out the co-ordinated hijackings from three airports. The pilot-hijackers turned off the aircrafts' transponders to make it more difficult for air traffic controllers to track their courses. The hijackers had volunteered for a suicide mission.
Militant disciples of bin Laden may, since the 1998 bombings of two US embassies in East Africa, have transformed themselves from 20th century holy warriors - mujahedeen - into 21st-century practitioners of intercontinental jihad, holy war.
At the trial of four mujahedeen convicted of involvement in those bombings, an al-Qa'ida member, Issam al-Ridi, revealed that he had been trained as a pilot in 1993. His expertise however was used only to ferry weaponry. Al-Qa'ida's interest in having pilots amongst its cadres seems to be more recent.
A former Afghan airlines pilot told a London-based Arabic daily that 14 young militants had received training on Afghan Boeing aircraft and left Afghanistan a year ago for an unknown destination.
The pilots who took part in Tuesday's operation had been in the US for a year receiving training at local flight schools. Some pilots were accompanied by their wives and children who conveyed an air of normality and respectability but revealed that the operation had a reasonably large budget showing that the militants have little difficulty raising funds from wealthy fundamentalists.
There could be more so-called sleepers in the US and elsewhere awaiting the signal to awake and strike. Thursday night's arrests of suspects attempting to board aircraft in New York demonstrate that hijacking remains a risk.
The threat posed by hi-tech mujahedeen could be compounded by the fact that some of those said to be involved in Tuesday's onslaught may have belonged to militant groupings other than al-Qa'ida.
The Egyptian Islamic Jihad has been mentioned as a possibility. Recruits could also come from mainstream Islamist formations found everywhere in the Muslim world. These movements, which draw members from the professions, are embedded in their local societies and make up for their governments' failure to provide health, educational and welfare services to the poor.
Thus, the Islamic International Brigades do not have to rely on the 15,000-odd Afghan veterans of the war in Afghanistan, who were seeded into the world like so many dragon's teeth when that conflict ended.
The brigades can tap into a vast reservoir of alienated Muslim youth. Al-Qa'ida, for one, continues to recruit and train mujahedeen for the unending civil war in Afghanistan and the struggle against the US. The men who carried out the US hijackings were in their late 20s and 30s, a second generation of holy warriors.
These militants are far more dangerous than the Palestinians who hijacked planes in the late 1960s and early 1970s.
They were not bent on suicide and had no intention of crashing planes and killing passengers or bystanders. Their aim was to secure publicity to win recognition for their people. They believed once this happened, the world would right the injustice done to them by Israel.
By contrast, today's mujahedeen harbour no illusions. They see the West, particularly the US, as their civilisational enemy. They are determined to punish the US for backing Israel against the Palestinians; imposing sanctions on Iraq, Libya and Sudan; deploying forces on the sacred soil of Saudi Arabia and supporting corrupt, undemocratic, repressive and "Godless" Arab and Muslim governments.
Unless their grievances are addressed, the 21st century holy warriors could strike again with devastating effect.