The United States needs to work more closely with Europe to stymie international terrorism, especially stopping westerners from flocking to the Islamic State, said Democratic presidential candidate Hillary Clinton.

The recent terrorist attack in Belgium, not six months after the Paris attacks, has raised concerns about European security and intelligence sharing. At a March 23 speech in California, Clinton highlighted some perceived security deficiencies among European Union nations.

"It’s actually easier for the United States to get flight manifests from E.U. nations than it is for E.U. nations to get them from their own neighbors, thanks to an agreement the U.S. negotiated when I was secretary of state," she said.

This claim intrigued us, so we reached out to some experts to see if Clinton was on target.

Clinton is talking about the United States–European Union Agreement on Passenger Name Records, a bilateral measure intended to increase the government’s ability to track who is coming into the country. The agreement was signed in 2011 and went into effect in 2012, when Clinton was in office.

As a result of this agreement, the European Union provides the United States Department of Homeland Security with passenger name records for every flight from a European Union country to the United States, and vice versa. Passenger name records are essentially very detailed flight manifests, containing information like how far in advance travelers bought their tickets, whether they made specific seat requests and even how many bags they checked. (The European Union has similar agreements with Canada and Australia.)

Every expert we queried pointed out that much of the negotiation legwork on this agreement took place before Clinton joined the State Department in 2009.

Though the agreement currently in effect was finalized while Clinton headed the State Department, this was the final in a series of negotiations and precursor agreements spanning about a decade following the Sept. 11, 2001, World Trade Center attacks. The standing 2012 version responded to Europeans’ information privacy concerns, and this final push happened during Clinton’s tenure.

"The agreement that Clinton was involved in is the culmination of successive agreements, beginning with the impact of 9/11," said Mai’a Cross, an expert in European foreign and security policy at Northeastern University.

So, while Clinton's role is up for some debate, the United States does get flight manifests from the E.U. But Clinton also said that all E.U. nations don't share that information with each other. That's accurate, at least for right now.

U.S. law requires passenger name record data for any flight entering or leaving the country, but the European Union currently does not. And flight information collection policies are not universal among all 28 European Union members.

For example, the United Kingdom has had its own passenger name record system in place for incoming flights, noted Kaija Schilde, an expert on Europe and transatlantic security at Boston University. She added that this issue is further complicated by the Schengen Area, a group of 26 European countries that allow passport-free travel between member countries.

So if the United States wants passenger information about a flight from Germany to the New York City, that is an easier get than if Germany wants the same passenger information about a flight from Italy, said Eva-Maria Maggi, a European Union expert at the University of Arizona.

This is a result of the U.S.-E.U. agreement but also the fact that the European Union doesn’t have a passenger name record policy similar to the United States, Maggi said.

To be clear, the United States does not collect this information for flights that do not enter or leave the United States, like an Italy to Germany flight.

Proponents of a European Union-wide system say one of the benefits of such a system is that it would harmonize these differences among member nations.

In fact, one such system is on the table, and experts told us the European Parliament will likely approve it in the next couple months. In direct response to the November 2015 terrorist attacks in Paris, the Council of the European Union approved text for a policy that would require passenger name record data for all international flights entering or leaving the European Union. The law would also allow, but not require, member states to collect passenger name records for flights between member countries.

Cross noted that passenger name records are just a narrow slice of intelligence information.

"If you’re talking intelligence sharing more generally, there has been more sharing within Europe than with other countries," she said.

Our ruling

Clinton said, "It’s actually easier for the United States to get flight manifests from E.U. nations than it is for E.U. nations to get them from their own neighbors, thanks to an agreement the U.S. negotiated when I was secretary of state."

Clinton’s claim is, for the most part, on target. The European Union has an agreement with the United States to provide passenger name records for all U.S.-E.U. air travel. While this was mostly negotiated before Clinton took office, the final push happened in 2011, when she was serving as secretary of state.

Countries within the European Union do not have a uniform passenger name record collection policy, so they might not be able to share the same information amongst each other as easily. However, the European Union is on the verge of enacting a policy that would require passenger name record collection for all flights entering and leaving the union.

We rate Clinton’s claim Mostly True.