As Operation Ripper showed that the PVA/KPA forces were withdrawing north of Seoul, US Eighth Army commander General Matthew Ridgway planned to block and attack the retreat of KPA I Corps.

At points generally along this line 6–10 miles (9.7–16.1 km) to the north, Milburn's patrols had made some contact with KPA I Corps west of Uijongbu and the PVA 26th Army to the east.

Operation Tomahawk would take place only if Ridgway received assurances that weather conditions on 23 March would favor a parachute drop, and that ground troops could link up with the airborne force within twenty-four hours.

If these assurances were forthcoming, the 187th Airborne Regimental Combat Team (187th RCT), with the 2nd and 4th Ranger Companies attached, was to drop in the Munsan-ni area on the morning of 23 March and block Route 1.

The ROK 1st Division, which would be following Task Force Growdon, was to relieve the 187th RCT upon reaching Munsan-ni, and the airborne unit then was to prepare to move south and revert to Eighth Army reserve.

[9] C-46 Commandos and C-119 Flying Boxcars of the 315th Air Division had begun lifting the airborne troops from the Taegu airfield shortly after 07:00, all heading initially for a rendezvous point over the Yellow Sea west of the objective area.

The replacement plane carrying the 1st Battalion commander and party had finally reached Munsan-ni, and its passengers had jumped in the correct zone not knowing that they would be the only troops in the area.

After Soule's forces encountered the strong PVA positions on the morning of 24 March, he ordered Bowen to pull in his patrols and prepare the 187th RCT for an eastward attack on the Route 2Y axis.

The 3rd Division met only light resistance when it resumed its attack from the south on March 25 and advanced 2 miles (3.2 km) beyond the hills where strong PVA positions had delayed it the day before.

Using Route 33 and a lesser road to the west, two tank columns from the 3rd Division joined Bowen's forces during the afternoon of 26 March, but, even with armored support, it was 09:00 the following day before the 187th captured Hill 228.

On the following day he had extended the Cairo Line from its original terminus in the Marine zone northeastward across the remainder of the army front to the town of Chosan-ni on the east coast.

Ridgway's forces achieved the adjusted line by the end of March, encountering no more than the sporadic delaying action that had characterized the opposition to Operation Ripper from the outset.

Thus, since 7 March Eighth Army forces had made impressive territorial gains, recapturing the South Korean capital and moving between 25–30 miles (40–48 km) north to reach the 38th Parallel.

Notwithstanding the building evidence of KPA offensive preparations, officials of the Departments of State and Defense believed that Ridgway's recent successes might have convinced the Chinese and North Koreans that they could not win a military victory and, if this was the case, that they might agree to negotiate an end to hostilities.

The consensus in Washington was that the Chinese and North Koreans would be more inclined to agree to a cease-fire under conditions restoring the status quo ante bellum, that is, if the fighting could be ended in the vicinity of the 38th Parallel where it had begun.

Therefore, while there was no intention to forbid all ground action above the parallel, there was some question in the mind of Secretary of State Dean Acheson and among many members of the United Nations whether the Eighth Army should make a general advance into North Korea.

Shortly before he received the Joint Chiefs' message he again had expressed his views in a letter to Republican Congressman Joseph William Martin Jr. of Massachusetts, the-minority leader in the United States House of Representatives.

[42] In acknowledging these conditions Ridgway notified MacArthur that he currently was developing plans for an advance that would carry Eighth Army forces 10–20 miles (16–32 km) above the 38th Parallel to a general line following the upstream trace of the Yesong River as far as Sibyon-ni (38°18′32″N 126°41′42″E / 38.309°N 126.695°E / 38.309; 126.695) in the west, falling off gently southeastward to the Hwach'on Reservoir, then running east to the coast.

These remarks prompted other governments to ask about a possible shift in US policy, and in Truman's judgment they so contradicted the tone of his own planned statement that he decided not to issue it for fear of creating more international confusion.

Upon his return to Tokyo late on 24 March following his conference with Ridgway and a visit to the front, he announced that he had directed the Eighth Army to cross the parallel "if and when its security makes it tactically advisable.

In advance of issuing orders for attacks above the 38th Parallel, Ridgway assembled corps and division commanders at his Yoju headquarters on March 27 to discuss courses of action that were now open to them or that they might be obliged to follow.

[50] Alluding to past and recent proposals of cease-fire negotiations, Ridgway also advised that future governmental decisions might compel the Eighth Army to adopt a static defense.

Ridgway agreed with MacArthur's earlier prediction that a stalemate ultimately would develop on the battlefront, but just how far the Eighth Army would drive into North Korea before this occurred, he informed the assembled commanders, could not be accurately assessed at the moment.

His intelligence staff later discovered that the bulk of the Corps had withdrawn behind the Yesong and also warned that the attack force would be vulnerable to envelopment by a fresh PVA unit located off the right flank of the advance.

[52] He planned to point his main attack toward the centrally located road and rail complex marked out by the towns of Pyonggang in the north and Ch'orwon and Gimhwa-eup in the south.

This complex, eventually named the Iron Triangle by newsmen searching for a dramatic term, lay 20–30 miles (32–48 km) above the 38th Parallel in the diagonal corridor dividing the Taebaek Mountains into northern and southern ranges and containing the major road and rail links between the port of Wonsan in the northeast and Seoul in the southwest.

A unique center of communications, the complex was of obvious importance to the ability of the communist high command to move troops and supplies within the forward areas and to coordinate operations laterally.

Ridgway's first concern was to occupy ground that could serve as a base both for continuing the advance toward the complex and, in view of the enemy's evident offensive preparations, for developing a defensive position.

Following the lower shoreline of the reservoir, it then turned slightly north to a depth of 10 miles (16 km) above the parallel before falling off southeastward to the Yangyang area on the coast.

They would create, in effect, a broad salient bulging above the Kansas Line between the Imjin River and Hwach'on Reservoir and reaching prominent heights commanding the Ch'orwon-Kumhwa base of the communications complex.