The mid-Atlantic gap that had previously been unreachable by aircraft was closed by long-range B-24 Liberators. On 18 March 1943, Roosevelt ordered King to transfer 60 Liberators from the Pacific theatre to the Atlantic to combat German U-Boats; one of only two direct orders he gave to his military commanders in WWII (the other was regarding Operation Torch). At the May 1943 Trident conference, Admiral King requested General Henry H. Arnold to send a squadron of ASW-configured B-24s to Newfoundland to strengthen the air escort of North Atlantic convoys. General Arnold ordered his squadron commander to engage only in "offensive" search and attack missions and not in the escort of convoys. In June, General Arnold suggested the Navy assume responsibility for ASW operations. Admiral King requested the Army's ASW-configured B-24s in exchange for an equal number of unmodified Navy B-24s. Agreement was reached in July and the exchange was completed in September 1943.