The US military must reevaluate its combatant command structure to determine whether certain commands are needed amid the current threats and budget constraints, Senator John McCain said in a US Senate hearing on military effectiveness on Thursday.

McCain noted that US lawmakers repeatedly hear how “dramatic increases in civilian and military staffs have persisted even as resources available for warfighting functions are increasingly strained.”

“We must ask whether the current combatant command structure best enables us to succeed in the strategic environment of the 21st century,” McCain stated. “Should we consider alternative structures that are organized less around geography than trans-regional and functional missions.”

Washington needs to examine, McCain argued, whether the US military needs some combatant commands such as Northern and Southern commands.

The Department of Defense would also need to review if there were “duplicative functions” in the Joint Staff, combatant commands as well as subordinate commanders that could potentially be streamlined.

McCain’s remarks come as the US military faces major expenses over the next decade for upgrades across the service branches. By the mid-2020s, the United States will need more than $700 billion in costs to modernize its nuclear triad.