Limited offensives were launched to maintain contact with the rice-growing regions of the northwest and along the Mekong River and Route 5, the Republic's overland connections to South Vietnam. The strategy of the Khmer Rouge was to gradually cut those lines of communication and squeeze Phnom Penh. As a result, FANK forces became fragmented, isolated, and unable to lend one another mutual support. The main U.S. contribution to the FANK effort came in the form of the bombers and tactical aircraft of the U.S. Air Force. When President Nixon launched the incursion in 1970, American and South Vietnamese troops operated under an umbrella of air cover that was designated Operation Freedom Deal. When those troops were withdrawn, the air operation continued, ostensibly to interdict PAVN/Viet Cong troop movements and logistics. In reality (and unknown to the U.S. Congress and American public), they were utilized to provide tactical air support to FANK. As a former U.S. military officer in Phnom Penh reported, "the areas around the Mekong River were so full of bomb craters from B-52 strikes that, by 1973, they looked like the valleys of the moon." On 10 March 1972, just before the newly renamed Constituent Assembly was to approve a revised constitution, Lon Nol suspended the deliberations. He then forced Cheng Heng, the head of state since Sihanouk's deposition, to surrender his authority to him. On the second anniversary of the coup, Lon Nol relinquished his authority as head of state, but retained his position as prime minister and defense minister. On 4 June, Lon Nol was elected as the first president of the Khmer Republic in a blatantly rigged election. As per the new constitution (ratified on 30 April), political parties formed in the new nation, quickly becoming a source of political factionalism. General Sutsakhan stated: "the seeds of democratization, which had been thrown into the wind with such goodwill by the Khmer leaders, returned for the Khmer Republic nothing but a poor harvest." In January 1973, hope was renewed when the Paris Peace Accords were signed, ending the conflict (for the time being) in South Vietnam and Laos. On 29 January, Lon Nol proclaimed a unilateral cease-fire throughout the nation. All U.S. bombing operations were halted in hopes of securing a chance for peace. It was not to be. The Khmer Rouge simply ignored the proclamation and carried on fighting.