Four Portuguese F-16 fighter jets and 150 Portuguese troops and civilians will be sent to Ukraine neighbor Romania in May and June to participate in NATO aerial policing missions, Romania's top defense body said Tuesday.

The defense body said it has approved a request from Romanian Prime Minister Victor Ponta to allow the planes and troops into the country.

Romania, which is on NATO's eastern flank, has hosted foreign troops and missions from other member countries since the Ukraine crisis broke out at the end of 2013. This is the first time Portuguese troops come to the country.

NATO decided earlier this month to set up command-and-control centers in Latvia, Estonia, Lithuania, Poland, Romania and Bulgaria in response to challenges from Russia and Islamic extremists.

In an emergency, the centers will help speed up the arrival of the new quick-reaction force as well as later NATO reinforcements.

FBI chief James Comey, who visited Romania Tuesday, said cyber security and fighting corruption and terrorism are priorities for both the U.S. and Romania.

Comey said that criminals can do damage all over the world through the Internet, which "makes all of us neighbors."

He added, "we must shrink the world in the same way as criminals have."

In recent years, Romania and the U.S. have cooperated in fighting terrorism, corruption and trans-national organized crime.

Romania's Intelligence Service director, Eduard Hellvig, said his country plays a key role in NATO providing cyber security for Ukraine.