US Secretary of State John Kerry called on Monday for the deployment of a 4,000-strong "protection force" to bolster the UN peacekeeping mission in South Sudan.
"There is absolutely no question that we need to move forward with the deployment of the regional protection force authorised by the UN Security Council," Kerry said after meeting with five regional foreign ministers in the Kenyan capital Nairobi.
Kenyan Foreign Minister Amina Mohamed also urged a speedy deployment. "When should it be there? Sooner rather than later," she said.
In the wake of fresh fighting in the South Sudanese capital Juba last month, Kenya offered to provide troops for a new force, approved by the Security Council on August 12, alongside Ethiopia and Rwanda.
The 4,000 new troops will join 12,000 already deployed as part of the UN Mission in South Sudan (UNMISS) which has been widely criticised for its serial failure to protect civilians.
Not an 'intervention force'
Mohamed said a "gradual deployment" would allow troops to reach Juba more quickly.
"Any number of soldiers that goes in in the name of a protection force would be welcome and would open the door to everything else," she said.
Kerry said the new force would only seek to improve security in Juba and allow for the implementation of a peace deal signed a year ago.
"This is not an intervention force, it is a protection force, with a very clear mandate to protect people, to ensure access, freedom of movement and to be free from ambush or attack of any sort," he said.
No timeline has been given for the deployment but South Sudan's government has expressed strong reservations over the plan and called for further discussions.
"We want to know the mandate of this protection force," said South Sudan Vice President Taban Deng Gai during a visit to the Sudanese capital Khartoum on Monday. "We want to sit with them in Juba, not in New York."
Deng is strengthening his position after seizing the vice presidency from his old friend and ally Riek Machar who was forced to flee Juba during last month's fighting.
Kerry signalled that Machar's ouster did not undermine the August 2015 peace agreement of which he was a key signatory. "Legally, under the agreement, there is an allowance for the replacement of personnel and that has been effected with the appointment of a new vice president," he said.
Kerry also announced an additional $138 million (122 million euros) in aid for South Sudan where 2.5 million people have been uprooted by war since December 2013 and close to half the population is in need of emergency food aid.
During his meetings in Nairobi Kerry also addressed the threat of terrorism emanating from Somalia where a new government is due to be chosen next month.
"Al-Shabaab may have had its start in Somalia but it doesn't care about national borders," Kerry said. "The terrorists are a regional threat and demand a regional response."
He pledged continuing support for the internationally-backed government in Mogadishu and the cash-strapped African Union force fighting the Shabaab in Somalia.