JUBA, South Sudan — The United States and Europe are urging political leaders in South Sudan to maintain calm after the president dismissed his vice president and entire cabinet.

The EU delegation to South Sudan on Thursday urged political leaders to resolve differences through dialogue, an implicit acknowledgement of the risk of violence that South Sudan faces after Tuesday's political shake-up.

The U.S. is "deeply concerned by the risk to stability posed by" President Salva Kiir's decision, the State Department said in a statement on Wednesday.

"The United States calls on all parties to maintain calm and prevent violence, and on the Government of South Sudan to quickly and transparently form a new cabinet. We encourage South Sudan do so in a manner that reflects the diversity of the South Sudanese people, and that respects its transitional Constitution and the democratic ideals the new country has espoused," it said.

Kiir dismissed his first vice president, Riek Machar, and suspended Pagan Amum, the secretary-general of the ruling SPLM party pending an investigation into charges of insubordination and creating social divisions within the party. After dismissing his cabinet, he reduced the number of ministries from 29 to 18.

On Wednesday there was heavy deployment of armed South Sudanese soldiers and police around the presidential palace. Heavily armed troops also guarded key government institutions including ministries. Those deployments appeared to return to normal levels on Thursday.

While Kiir is leader of the ruling SPLM party, many of the dismissed ministers, including Machar and Amum, were key figures in the rebel movement that fought a decades-long war against Sudan that led to South Sudan's independence in 2011

Reports of a power struggle in the ruling party have persisted, particularly between Kiir and Macher, who had said he is interested in running for president in 2015.

Amum, South Sudan's chief negotiator in talks with Sudan, has expressed interest in leading the ruling party and in recent days has been critical of Kiir's leadership. Given that South Sudan is almost a one party state, winning leadership of the party effectively means an automatic ticket to the presidency.

Analysts expressed fear that Kiir's dismissals could lead to tribal clashes.

"This reshuffle has happened at a critical time when there is tension within the ruling SPLM party as people posture for the general elections in 2015,"said Zachariah Diing Akol, of the Sudd Institute, a local think tank. "Our fear is that there might be chaos and tribal clashes. We hope the leaders will urge their communities to remain calm," Akol added.

However, Charles Manyang D'awol, undersecretary in South Sudan's foreign affairs ministry dismissed such fears.

"There is spiraling propensity to misconstrue this move as an internecine power struggle that might, somehow, ignite some kind of instability or unrest in this country. Contrary to this assumption, the move is legitimate exercise of powers by the Head of State," said D'awol.

While some commentators on social media expressed support for Kiir's decision to reduce the number of ministries from 29 to 18 others were critical of his action against Amum and Machar, describing it as move aimed as an extension of internal party politics into national politics.

However, D'awol argued that the suspension of Amum marked "a significant turn in the way the ruling party has been running its affairs. It has been a positive endeavor to bring more transparency and accountability to the way business is conducted in the party," said D'awol.

Barnaba Marial Benjamin, former government spokesman and information minister, urged the country to remain calm.

"This is a normal democratic process where an elected head of state, elected by 93 percent of the country, has decided to change his government (and) he should be given the chance to for a new government," he said.

Benjamin dismissed fears that the dissolution of cabinet would lead to chaos.

"I think some of the people removed are among the most committed people to the liberation struggle of this country and they would not want to destabilize the country. Secondly, we know that a government reshuffle is normal," said Benjamin. "We are not popes you know. Being a minister is not a pope's position."