Al-Qaeda's supremo in Yemen -- Osama bin Laden's ancestral homeland -- has warned Americans of a bloodier jihadist struggle to come following the terror mastermind's killing by US commandos.
The warning from Al-Qaeda in the Arabian Peninsula came as top US Senator John Kerry announced a trip to mend fences with a resentful Pakistan, where bin Laden was gunned down, but also to seek answers on how he came to be there.
AQAP leader Nasir al-Wahishi said in a statement posted on an Islamist website that the "ember of jihad (holy war) is brighter" following the May 2 death of bin Laden, according to the SITE monitoring group Wednesday.
The Yemen-based fugitive warned Americans not to fool themselves that the "matter will be over" with the killing of bin Laden, the Saudi-born architect of the September 11, 2001 attacks.
"Do not think of the battle superficially ... What is coming is greater and worse, and what is awaiting you is more intense and harmful," Wahishi said, according to a SITE translation.
"We promise Allah that we will remain firm in the covenant and that we will continue the march, and that the death of the sheikh will only increase our persistence to fight the Jews and the Americans in order to take revenge."
The United States has warned of the threat posed by Islamist militancy in Yemen, the homeland of bin Laden's father, and has warned of the potential for the country to become a new staging ground for Al-Qaeda.
The AQAP was born of a January 2009 merger between the Saudi and Yemeni Al-Qaeda branches. It claimed a failed attempt to bomb a Detroit-bound US airliner in December 2009, and was accused last October of sending parcel bombs addressed to US synagogues that were disguised inside computer printers.
Four days after bin Laden was killed in the US raid on his sprawling compound, about two hours' drive from the Pakistani capital Islamabad, a US drone attack targeted US-Yemeni cleric Anwar al-Awlaqi in southern Yemen.
The cleric, who Washington says has strong links to Al-Qaeda, survived the attack but two AQAP members were killed.
The discovery of bin Laden in the Pakistani garrison town of Abbottabad after a decade-long manhunt has plunged testy relations between Islamabad and Washington deeper into trouble.
Pakistan is an uneasy ally in the US-led war against the Taliban and Al-Qaeda insurgency in neighboring Afghanistan, and receives billions of dollars in US aid annually.
Senator Kerry said that when he traveled to Pakistan early next week, he hoped to resolve some of the puzzles lingering since the Al-Qaeda leader was finally unearthed and shot dead by elite US Navy SEALs.
"There are some serious questions, obviously, there are some serious issues that we've just got to find a way to resolve together," Kerry, who chairs the Senate Foreign Relations Committee, told reporters.
But the Democratic ally of President Barack Obama also stressed the need to discuss the aftermath of bin Laden's death "and how we get on the right track" with Pakistan.
There are mounting allegations that bin Laden evaded capture for years thanks to the complicity or incompetence of Pakistan's authorities including its vaunted intelligence agency.
But Pakistan's civilian government, while vowing a full investigation, has angrily dismissed the allegations and its powerful military has warned of unspecified reprisals if another unilateral US raid were to occur.
The White House has called on Islamabad to help counter the growing mistrust by granting US investigators access to three of bin Laden's wives detained after the raid.
Pakistan said it had received no formal request for access to the women, as the sons of bin Laden broke their silence Tuesday to denounce his "arbitrary killing" and burial at sea, and to demand the relatives' release.
But with some US lawmakers clamouring for cuts in aid to Pakistan, another senator urged Islamabad to heed US "concerns" about its efforts to combat extremism, and give American interrogators access to the women.
"I think it's important that we have a good relationship with Pakistan, but not at any price," Senate Armed Services Committee chairman Carl Levin warned.