Sen. Rand Paul (R-Ky.) sent a lengthy letter to Senate Majority Leader Harry Reid (D-Nev.) today asking to table the immigration reform bill until the Boston attacks are better understood and national security considerations are addressed in the legislation.

“The facts emerging in the Boston Marathon bombing have exposed a weakness in our current system. If we don’t use this debate as an opportunity to fix flaws in our current system, flaws made even more evident last week, then we will not be doing our jobs,” Paul wrote.

“We should not proceed until we understand the specific failures of our immigration system. Why did the current system allow two individuals to immigrate to the United States from the Chechen Republic in Russia, an area known as a hotbed of Islamic extremism, who then committed acts of terrorism? Were there any safeguards? Could this have been prevented? Does the immigration reform before us address this?”

One of the Tsarnaev brothers accused in the attack was a naturalized citizen and the other a permanent resident. Paul said committee work needs to be done to scrutinize whether the system “gives individuals from high-risk areas of the world heightened scrutiny.”

“In the wake of 9/11, there was a comprehensive reform of our intelligence gathering system, yet our improved intelligence gathering system did not adequately detect these extremists. We need to understand possible intelligence failures and craft solutions,” he wrote.

Paul suggested revisiting the National Security Registration System (NSEERS) implemented by Congress in 2002 but suspended by Homeland Security Secretary Janet Napolitano in 2011.

“Our refugee programs have proven to be a problem. On, January 29, 2013, two Iraqi citizens living in Bowling Green, in my home state of Kentucky, were sentenced to long prison terms for participating in terrorism and providing material support to terrorists while living in the United States. How did this happen? Does the current immigration reform address how this might have happened? We may need more scrutiny when accepting refugees from high-risk nations,” he wrote.

“I want to make sure that any new bill addresses the visa entry and exit programs, in addition to refugee programs that have proven problematic in Bowling Green and possibly, if media reports are correct, in Boston.”

Paul added student visas need a second look, as well. “Should we suspend student visas, or at least those from high-risk areas, pending an investigation into the national security implications of this program?”

“I respectfully request that the Senate consider the following two conditions as part of the comprehensive immigration reform debate: One, the Senate needs a thorough examination of the facts in Massachusetts to see if legislation is necessary to prevent a similar situation in the future. Two, national security protections must be rolled into comprehensive immigration reform to make sure the federal government does everything it can to prevent immigrants with malicious intent from using our immigration system to gain entry into the United States in order to commit future acts of terror.”