Try as they might, the UN air forces could not prevent the arrival of the 2,900 tons of rations, fuel, ammunition, and other supplies needed every day by the 58 Communist divisions at the front. The enemy during this period was increasing his own air potential. On 17 June the Fifth Air Force warned that the Communists had stepped up their number of planes from an estimated 900 in mid-May to 1,050 in mid-June. Their Korean airfields were being kept under repair in spite of persistent UN air attacks. In June enemy light planes made night raids along the UN front lines and even into the Seoul area. VMF(N)-513 pilots, flying the nightly combat patrol over Seoul, had several fleeting contacts with these black-painted raiders. The Marines were unable to close in for the kill, since the opposing planes were nonmetal and difficult to track by radar. Soon, however, the VMF(N)-513 pilots had better hunting. On 30 June Captain Edwin B. Long and his radar operator, CWO Robert C. Buckingham, shot down a black, two-place PO-2 biplane. And on 13 July Captain Donald L. Fenton destroyed another.[267] [267] MAG-12 HD, Jun 51, Summary and Chronology, 30 Jun; MAG-12 _HD_, Jul 51, Chronology, 13 Jul. Despite the Air Force emphasis on interdiction, better close air support remained a major objective of the 1st MAW. One of the requirements was a shorter flying distance from air base to combat area. K-46, the MAG-12 field near Hoengsong, had qualified with respect to reduced flying time. Maintenance problems caused by the dusty, rocky runway of this primitive strip led to its abandonment. On 14 July the squadrons pulled back temporarily to K-1, and on the 26th MAG-12 withdrew its maintenance crews. The Group’s new field was K-18, a 4,400-foot strip on the east coast near Kangnung and just south of the 38th Parallel. Situated only 40 miles behind the 1st Marine Division and on the seacoast, the new field seemed to be ideally located. The runway, reinforced with pierced steel planking, extended inland from a beach where water-borne supplies could be delivered, as at K-3.[268] [268] “Rpt of Visit to Far East by CG, FMFPac, and his staff during the period 27 August to 12 September 1951,” 17 _ff._ _The Division Back in Action Again_ Political causes had a good deal to do with the renewal of activity for the 1st Marine Division late in August 1951. Apparently the Communist armed forces had been given enough time to recuperate from their hard knocks in May and June. At any rate, the Red delegates walked out on the truce talks after falsely charging on 22 August that UN planes had violated the neutrality of the Kaesong area by dropping napalm bombs. Although the Reds were unable to show any credible evidence, the negotiations came to an abrupt end for the time being.[269] [269] Berger, _The Korean Knot_, _op. cit._ 144–145.