U.S. Sen. Brian Schatz was one of eight senators who introduced a bill Tuesday to prohibit President Donald Trump from starting a pre-emptive war against North Korea without authorization from Congress.

The bill, according to a news release from Schatz’s office, was introduced amid the escalation of rhetoric between Trump and North Korean leader Kim Jong Un, and prohibits U.S. funds from being used without congressional approval unless the country faces imminent threat.

Schatz joined Chris Murphy (D-Conn.), Tammy Duckworth (D-Ill.), Cory Booker (D-N.J.), Bernie Sanders (I-Vt.), Jeff Merkley (D-Ore.), Elizabeth Warren (D-Mass.) and Tom Udall (D-N.M.) on the bill.

“Our bill makes it clear that the president does not have the authority to engage in preventive war without approval from Congress, and it goes so far as to tie the purse strings so that the president will have to ask for congressional approval before taking any preventive action,” Schatz said.