Children displaced by violence in South Sudan. Photo: UN/Isaac Billy.

One year ago today (January 9), millions of Southern Sudanese stood in long lines to vote for independence in a national referendum. The sense of hope and the inspiration that I experienced last year in the streets of Juba when people gathered to celebrate the official birth of this new nation has been undermined by mass killings perpetrated by the forces of Sudan President Omar al-Bashir and inter-ethnic strife in the south. And things are getting worse.

The citizens of the newest nation on earth need and deserve more from us. The United States and international community must immediately take robust action to address the ongoing inter-ethnic violence in South Sudan and attacks by Bashir’s forces which are creating a new, massive humanitarian disaster.

Recent accounts of thousands being massacred in escalating ethnic violence – and a looming humanitarian disaster – underscore what is at stake and why more of the same cannot be an option.

Fighting between ethnic groups in South Sudan is taking a devastating toll. In 2011, more than a thousand South Sudanese were killed in tribal violence. Just last week, inter-ethnic fighting in the country’s Jonglei State is estimated to have killed hundreds and, according to some reports, possibly thousands. This worsening pattern of death and destruction threatens to spiral out of control without intervention.

Sudan’s President Bashir has committed acts of war against South Sudan, launching a series of attacks across the border since November. These attacks have killed innocent civilians and members of South Sudan’s armed forces, which are already stretched far too thin. Instead of imposing consequences for the actions of Sudan’s Bashir, the United States has publicly urged South Sudan not to respond in its own defense.

It is not enough to host a conference on South Sudan’s development needs, as the administration did last month in Washington. Increased and sustained diplomatic and material support is needed for the already overstretched UN Mission in South Sudan, including more peacekeepers for civilian protection and provision of helicopters to allow quick access to areas threatened by ethnic violence.

But any level of support will fail as long as Omar al-Bashir, Sudan’s president and international criminal wanted for genocide, is allowed to continue his relentless assaults on innocent civilians on both sides of the border. President Obama and other world leaders must once and for all get serious and get tough on Bashir, hold him fully accountable and stop the damage he continues to inflict with impunity. The President needs to lead the international community to expand Sudan sanctions, secure immediate access for humanitarian aid organizations while providing a robust investment in humanitarian aid, and expand the mandate of the International Criminal Court. This must be done immediately and involve the highest levels of government leaders.

As I said in a news release last week, the stakes are too high for piecemeal approaches and timidity. This is being reinforced almost daily with news from South Sudan and the border regions within Sudan including Blue Nile and South Kordofan.

We know that when the United States Government is paying attention and exercising its influence, progress can be achieved. And, we know that the strength of our voices so often mark that fine line between government action and indifference.

Many of the people who I met in South Sudan expressed gratitude for the attention and activism of so many in the United States that made hope – and independence – possible. More attention and more activism will be needed to restore hope – and peace – to a battered and beleaguered people.

Tom Andrews is the President of United to End Genocide, which has just marked its one-year anniversary.