Some members of Congress are worried the rising levels of foreign investment in U.S. commercial real estate could have dangerous implications for national security.

Three lawmakers in particular — Senate Banking Committee ranking member Sherrod Brown, ranking member on the Homeland Security and Governmental Affairs Committee Claire McCaskill and Senate Finance Committee member Ron Wyden — requested the Government Accountability Office look into how foreign investment in U.S. real estate is examined. Specifically, the senators want to know if the government has the tools to deal with potential national security threats linked to foreign investment, CoStar reports.

The National Committee on U.S.-China Relations said Chinese investors have pumped almost $30B directly into U.S. real estate since 1990. The majority of  this investment happened after 2010 and has targeted major U.S. markets like New York City, Los Angeles and Chicago, among others.

More recently, China Life Insurance acquired a 95% stake in a portfolio of 48 U.S. properties valued at $950M. Most of these properties are in secondary and tertiary markets as investors increasingly bypass prime locations due to high prices.