Senator Brown says the U.S. and its allies need to work more closely with less reliable partners like Russia on intelligence gathering. He opposes sending more U.S. troops to the Middle East in response to the Paris attacks, or closing U.S. borders to refugees from Syria. But Brown says the screening process needs to be elevated.

“As desperate and poor as pretty much most of them are, but making sure that as we embrace people from other countries who flee violence and flee political harm if you will, that we as a nation look more closely as we admit political refugees.”

French officials say one of the Paris attackers was a refugee from Syria, one of the places where the terrorist group ISIS originated. The Obama administration has said 10,000 Syrian refugees will be allowed into the U.S. next year.