Operation Chenla I was an operation of the Vietnam War. The Cambodian armed forces launched the operation during late August 1970 with limited air support from the South Vietnamese army and air force. The operation was terminated in February 1971, after the Cambodian High Command made a decision to withdraw some units from Tang Kauk to protect Phnom Penh after Pochentong airbase was attacked. The objective of the operation was to reconnect Skoun and Kompong Cham along Route 7, which was repeatedly attacked by Communist forces.
Initially the Cambodian operation went as planned. Tang Kauk was retaken during early September with ease. The Cambodian military helped resettle refugees and set up local self-defense forces.
In response to Operation Chenla I, the North Vietnamese Army and Viet Cong launched a series of attacks on Cambodian positions on Route 7; the areas around Kompong Cham and Prey Totung were scenes of significant fighting during the closing months of 1970. As a result of pressure from the Viet Cong 9th Division, the Cambodian army couldn't advance beyond Tang Kauk.
South Vietnamese forces joined the Cambodian operation east of the Mekong River in December, allowing the Cambodian army to reopen Route 7 without making contact with enemy troops.
On the night of January 21, 1971, a force of about 100 North Vietnamese special forces armed with explosives and rocket launchers mounted an attack on the Cambodian air force base of Pochentong. The area surrounding Pochentong was also under attack. President Lon Nol of the Khmer Republic extended the 'State of Emergency' for another six months as Cambodian units from Tang Kauk were redeployed to protect the capital Phnom Penh, effectively terminating Chenla I.
Despite early gains the Cambodian military only achieved a limited strategic success; the North Vietnamese and Viet Cong still controlled a large portion of territory outside Phnom Penh. The attack on Pochentong airbase during the night of January 21 nearly wiped out the entire Cambodian air force, destroying all MiG jet fighters. Lon Nol was evacuated by U.S aircraft for treatment at Tripler General Hospital after suffering from a severe stroke.