The U.S. military has rushed its advanced anti-missile system to Israel and it is now "in place," Defense Secretary Lloyd Austin said.

THAAD, or the Terminal High Altitude Area Defense system, is a critical part of the U.S. military's layered air defense systems and adds to Israel's already formidable anti-missile defenses.

"The THAAD system is in place," Austin said, speaking to reporters before his arrival in Ukraine on Monday.