KUALA LUMPUR, Malaysia (AP) — Thailand and Cambodia agreed Thursday to establish interim observer teams to monitor a fragile ceasefire that ended five days of of deadly armed border clashes, even as the fate of 18 Cambodian soldiers captured by Thailand remains unresolved.

Cambodia and Thailand agreed to maintain a ceasefire and allow neutral monitors, as the US cited a “high level of distrust” between the Southeast Asian neighbors after their deadliest border clashes in decades.

Both sides agree to extend truce, though Thailand still holds 18 Cambodian soldiers taken hours after truce implemented.