Airliners sit on the tarmac at Dubai airport Oct. 31, a day after a parcel bomb was intercepted in Dubai originating in Yemen.NEW: Yemen needs help to fight al Qaeda, a top official saysNEW: A Yemeni student arrested and released over the plot says she is innocentNEW: South Korea boosts airport controls ahead of a summit of world leaders next weekSuspected al Qaeda bomber Hassan al-Asiri is connected to the plot, an official says(CNN) -- Yemen is tightening security at all of its airports in the aftermath of a plot to send bombs from Yemen to the United States, the country's National Civil Aviation Security Committee said Monday.
"Every piece of cargo and luggage will go through extensive searching" at all of its airports, the agency said.
Cargo companies such as DHL, FedEx and UPS will be required to make more stringent checks before accepting any package, according to the committee.
But Yemen needs "a lot of help" to fight al Qaeda, an aide to the country's prime minister told CNN Monday.
"Al Qaeda has got a global sort of agenda, so you need global collaboration and regional collaboration," Mohammed Qubaty said.
"We need a lot of help as regards security information, logistics," and new ways to confront them, he said, even as he emphasized that Yemen does not want foreign troops on it soil.
"We have got our security and our armed forces on the ground there," he said, saying the country does not want to become another Iraq, presumably referring to the 2003 U.S. invasion.
The U.S. military commander credited with helping reduce violence in Iraq said Washington had been concerned about Yemen for some time.
"When I was the commander in Iraq we already saw the problems starting to loom in Yemen," Gen. David Petraeus told CNN.
He said that when he was in charge of all U.S. military forces in the region, "We did focus a great deal of additional attention on helping our Yemeni partners there and the events of recent days have shown why that was valid."
On Friday, authorities in the United Arab Emirates and Britain found two packages with explosives that were destined for synagogues in Chicago, Illinois.
The explosive found in the United Arab Emirates Friday may have traveled on passenger planes to get there, airline officials said Sunday.
Both explosives appear to have been designed to detonate on their own, without someone having to set them off, the top White House counterterrorism official told CNN.
"It is my understanding that these devices did not need somebody to detonate them," said John Brennan, President Barack Obama's assistant for homeland security and counterterrorism.
South Korea is also stepping up security ahead of a summit of world leaders next week, it announced Monday.
Anybody who's associated with al Qaeda in the Arabian Peninsula is a subject of concern.--John Brennan
Incheon International Airport will inspect all air cargo coming from destinations on the list of nations that sponsor terrorism, South Korean customs said Monday.
U.S. investigators believe al Qaeda bomb maker Ibrahim Hassan al-Asiri, 28, is linked to that package and another one found on the airplane in Britain's East Midlands Airport on Friday, a federal official, who was briefed by authorities, told CNN Sunday.
Al-Asiri, who is thought to be in Yemen, is a Saudi who was high on Saudi Arabia's list of most wanted published in February 2009. He is also believed to be the bomber who designed last year's failed Christmas Day underwear bomb.
Separately, an engineering student arrested in Yemen was released Sunday, along with her mother, according to her father, Mohammed Al-Samawi.
Human rights attorney Abdul-Rahman Barman earlier identified her as Hanan Al-Samawi, a fifth-year student at Sanaa University in the Yemeni capital.
A high-level source in the United Arab Emirates said Hanan Al-Samawi's name was found on the cargo manifest of the device found in Dubai.
She said Monday she was not guilty.
"I am totally innocent and there is no proof against me, and that's why I have been released," she said.
Authorities do not have any American suspects at this time, a U.S. official said.
Two schools in Yemen were being looked at in connection with the plot and had been on the radar of U.S. officials before, the official said.
The explosive device found in Dubai, United Arab Emirates, was contained in a Hewlett-Packard printer, and had a motherboard originating from a mobile phone, but did not have a SIM card in it, the high-level source told CNN.
The device was professionally assembled, the source said. The motherboard was connected by a striker to the printer head and then to the cartridge, which was filled with explosives.
Authorities have the serial number of the motherboard and the printer, and are searching to see where it was sold, how it was paid for and what information they can glean about the people who performed those transactions, according to the source.
Authorities believe an explosive device found at the United Kingdom's East Midlands airport flew from Yemen to a Persian Gulf state, then to Cologne, Germany, the official said. The device was then transferred onto a UPS plane.
Investigators are still attempting to retrace the route of the Dubai device, according to the high-level official. Some believe it went to Doha, Qatar, on Qatar Airways, where it spent the night before traveling to Dubai the following day. However, it does appear the devices did fly on commercial passenger planes, the high-level official said.
Screening the devices would have been difficult, since printers normally contain computer parts and wires, according to Richard Quest, CNN's aviation correspondent.
The two devices found Friday look like they were put together by the same bomber who designed last year's failed Christmas Day underwear bomb, a U.S. government official told CNN.
"The thinking is it's the same person or group of people that built the underwear bomb, because of the way it's put together," said the official, who had been briefed by multiple U.S. authorities and law enforcement sources. "But this one is about four times as powerful."
American authorities are now endorsing British Prime Minister David Cameron's position that the explosives were designed to take down an airplane, the official said. However, a U.S. official said Sunday the United States has not drawn any conclusions on the intent of the bombs and whether they were intended to explode in flight, at the synagogues or somewhere else.
American and British authorities think al Qaeda's branch in Yemen is linked to the plot.
A key figure in the group is the American-born Yemeni militant cleric Anwar al-Awlaki, whom U.S. authorities have linked to Fort Hood shooting suspect Maj. Nidal Hasan and the man accused in the Christmas Day bomb attempt.
Brennan on Friday declined to name al-Awlaki specifically as a suspect.
"Anybody who's associated with al Qaeda in the Arabian Peninsula is a subject of concern," he said.
The U.S. Transportation Security Administration is sending six inspectors to Yemen to help improve cargo security, an official with the agency said Sunday.
"Even before this incident, 100 percent of identified high-risk cargo on inbound passenger planes was being screened," TSA Administrator John S. Pistole said in a statement Sunday, noting that security procedures will evolve based on the latest intelligence information.
Over the past several months, Yemen, which wants to be seen as a committed partner in the fight against terrorism, has launched several offensives against al Qaeda in its country, but has not captured al-Awlaki.CNN's Caroline Faraj, Bharati Naik, Caroline Paterson, Jeanne Meserve, Mohammed Jamjoom, Susan Candiotti and Carol Cratty contributed to this report.