Foreign ministers from NATO member states gathered in Antalya, Turkey, on Thursday to debate a U.S. proposal to significantly boost defense spending amid growing global threats and shifting American strategic priorities.

U.S. Secretary of State Marco Rubio said on Thursday that all NATO members will have agreed on a goal of spending the equivalent to 5% of GDP on defense over the next decade by the 2025 NATO Summit in June.

Slovenia and several NATO member states are seeking ways to expand the definition of defense spending as they attempt to meet US calls to allocate more funds on security, the nation’s prime minister said.