Although taking no personal responsibility for the bombings, which have sent tremors through the vulnerable, oil-rich states of the Arabian peninsula, Bin Laden insisted that the killing of the Americans in Khobar (Dhahran) just over two weeks ago demonstrated the depth of hatred for Americans in Saudi Arabia. "Not long ago, I gave advice to the Americans to withdraw their troops from Saudi Arabia," he said. "Now let us give some advice to the governments of Britain and France to take their troops out - because what happened in Riyadh and Khobar showed that the people who did this have a deep understanding in choosing their targets. They hit their main enemy, which is the Americans. They killed no secondary enemies, nor their brothers in the army or the police of Saudi Arabia ... I give this advice to the government of Britain."
Bin Laden, most of whose immensely wealthy family have remained loyal to King Fahd, has been accused by Western and Arab governments of being "the financier of an Islamic international army", training fighters to oppose the governments of Algeria and Egypt as well as Saudi Arabia. And in his long and sombre interview, he expressed his contempt for the Saudi monarchy and its failure to abide by Islamic sharia law, adding that the "evils" of the Middle East stemmed from America's attempt to take over the region and from its support for Israel. My journey to him took me across miles of devastated villages and fields in the rocky mountainsides of the country where he once fought Soviet invaders, and it culminated in a remote village where dozens of his mujahedin, dressed in Afghan clothes, stood guard as he spoke.
In Saudi robes - and sitting next to his two teenage sons, Omar and Saad - Bin Laden revealed that he had arrived here from Sudan on 18 May with his fighters, after the Saudis and Americans had put pressure on the Khartoum military government to expel him. He claimed that he would carry on a campaign from Afghanistan to set up a "true" Islamic state under sharia law in Saudi Arabia which, he said, had been turned into "an American colony".
When I asked if he was declaring war on the West, he replied: "It is not a declaration of war - it's a real description of the situation. This doesn't mean declaring war against the West and Western people - but against the American regime which is against every Muslim."
As he spoke, armed Egyptians, Saudis, Algerians and Afghans patrolled the night-time fields around us, their presence revealed by a single hissing gas lamp. At one point, Bin Laden broke off our conversation to pray, alongside his Arabs, on straw matting laid out in the field. Every few minutes, gunfire could be heard from the mountains to the east. "The explosion in Khobar," he said, "did not come as a direct reaction to the American occupation but as a result of American behaviour against Muslims, its support of Jews in Palestine [sic] and the massacre of Muslims in Palestine and Lebanon - of Sabra and Chatila and Qana - and of the Sharm el-Sheikh [anti-terrorist] conference."
Bin Laden's arrival back in Afghanistan after five-and-a-half years in Sudan marks a new stage in the campaign of the Organisation of Advice and Reform.
He accused the Saudi royal family of promising sharia laws while allowing the United States "to westernise Saudi Arabia and drain the economy". He blamed the Saudi regime for spending $25bn in support of Saddam Hussein in the Iran-Iraq war and a further $60bn in support of the Western armies in the war against Iraq in 1991, "buying military equipment which is not needed or useful for the country, buying airplanes by credit" - while at the same time creating unemployment, high taxes and a bankrupt economy.
"The safest place in the world for me is Afghanistan," he said.
When I suggested to Bin Laden that Afghanistan was the only place - rather than the safest - in which he could campaign against the Saudi government, he and some of the Arab fighters around him burst into laughter. "There are other places," he replied.
Did he mean Tadjikistan, I asked? Or Uzbekistan? Or Kazakhstan? "There are several places where we have friends and close brothers - we can find refuge and safety in them." When I said that he was already a hunted man, he dismissed my comment with contempt. "Danger is a part of our life - do you not realise that we spent 10 years fighting against the Russians and the KGB? ... When we were fighting the Russians here in Afghanistan, 10,000 Saudis came here to fight over a period of 10 years."
Osama Bin Laden clearly believes he now represents the most formidable enemy of the Saudi regime and of the American presence in the Gulf. Both are probably right to regard him as such.