DOHA, Qatar -- Homeland Security Secretary Janet Napolitano on Sunday met with top officials in Qatar, a highly prized Middle East ally whose lagging progress on aviation security has caught the U.S. government's attention, officials told Fox News. 

A series of meetings around the capital city began with the signing of a "letter of intent" at Qatar's interior ministry, indicating both countries "will be working together on a lot of the issues" facing aviation security, Napolitano told Fox News in a preview of the sessions. 

"This is part of weaving together (the) international architecture that's going to need to exist now and for the future," she said. 

Asked whether Qatar is a strong partner in securing the global aviation system, Napolitano said, "Well, we're going to have some discussions today about that." 

A U.S. official said her meetings Sunday would be a continuation of "candid conversations" with other counterparts around the world. 

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Napolitano's visit to Qatar follows an unannounced trip to Afghanistan to evaluate her agency's efforts to train Afghans in border security and customs techniques. 

Napolitano told Fox News that while the "letter of intent," signed by herself and Qatari interior minister Sheikh Abdullah bin Nasser Al Thani, is not a formal contract, it is "an indication that we know that we need to have a closer tie with (Qatar) on things like cargo, and they need to have a closer tie with us." 

In October, two explosives-laden packages sent from Yemen to the United States were intercepted. One was discovered in the United Arab Emirates, Qatar's neighbor, after flying on a Qatar Airways passenger jet. 

In the wake of that failed plot, U.S. counter-terrorism officials have focused on ensuring items shipped around the world are properly screened. One U.S. official said Qatar is "increasingly important" with its growing role as a hub for international travel and trade. 

Qatar is building a massive, technology-driven airport in Doha. It's expected to open in 2015 and accommodate significantly more passengers a year than the current leading airport in Qatar's capital. 

"Homeland security does not begin at America's borders," Napolitano said in a statement after Sunday's meetings. "It starts with our international partnerships to detect and deter terrorists." 

When asked whether Qatar needs to do more to secure the skies, the U.S. official said terrorists and criminals are "collaborating and putting their minds and technology to work, (and) the international community must do no less and constantly strive to improve our coordination, share best practices and modernize our technology." 

In the statement issued late Sunday, the Department of Homeland Security said the letter of intent recognizes the expanded responsibility to cooperate. 

The letter outlines several areas for improvement, including better information-sharing related to terror suspects, enhanced passenger screening at airports and boosted behavior detection capabilities, particularly those aimed at combating bulk-cash smuggling and money laundering, according to the statement. 

Qatar is a key U.S. ally in the Middle East with its moderate Muslim population. Smaller than the size of Connecticut, Qatar has a population of about 840,000 which is nearly 80 percent Muslim. 

Fox News is exclusively joining Napolitano on a week-long, security-focused trip to Europe and the Middle East, including a New Year's Eve stop in Afghanistan. After Qatar, she is going to Israel and Belgium.