WASHINGTON (AP) — Top U.S. military officers in the Asia-Pacific region say budget cuts could hurt the ability of American forces to respond to a security crisis, including on the Korean peninsula.

Pacific commander Adm. Samuel Locklear says U.S. allies are starting to question U.S. “staying power” as a guarantor of security.

Locklear and Gen. Curtis Scaparrotti who commands U.S. forces in South Korea were testifying Tuesday before the Senate Armed Forces Committee on the defense budget for 2015.

Scaparotti said U.S. forces in Korea are “fully resourced” but he voiced concern about the readiness of “follow-on” forces that would be needed if a security crisis broke out on the divided peninsula.

Scaparotti said North Korean leader Kim Jong Un is less predictable than his predecessor and poses a greater threat.