Like the UN's mission before it, Eulex has yet to bring to book those involved in politically motivated crimes in Kosovo.

When it comes to international engagement with the Balkans, it is a sad truth that violence always concentrates minds in Brussels and New York. So it is with the recent upsurge in Kosovo's northern municipality of Mitrovica. Last week, there was a special UN Security Council session on 6 July, expressions of concern by the European Council president, Herman Van Rompuy, during a visit to Kosovo by the same day, and a debate in the European Parliament on 7 July.

What brought this flurry of engagement? On 5 July, a Serb member of the Kosovo Assembly, Petar Miletić, was shot in the leg as he left home in the town's Serb-dominated north. Miletić is a senior official of the Serb Liberal Party, currently part of Kosovo's ruling coalition. The attack came days after an explosion on 2 July in the northern part of the town killed one person and injured 11. The explosion occurred during a protest by Serbs against the opening of an office by Kosovo's government, which the protesters, like most Kosovo Serbs, do not recognise.

The identity and motivation of those behind both the shooting and the explosion are not clear. But political tensions are running high ahead of a decision by the International Court of Justice, expected on 22 July, on the legality of Kosovo's declaration of independence in 2008.

Both recent incidents in Mitrovica were unequivocally condemned by the authorities in Pristina and Belgrade, as well as by all the main international actors in Kosovo, including the EU police and justice mission and the UN. While these condemnations are important, they are hardly sufficient. To break the cycle of political violence in Kosovo, more forceful action is required.

A key step would be to raise the cost of political violence. That in turn would require criminal accountability for those who participate in such acts. The record of those who have run Kosovo, including the UN, of bringing to justice those responsible for politically motivated violence remains weak, though. The post-1999 retaliation attacks against Kosovo's minorities, as well as attacks against some ethnic-Albanian political figures, remain largely unpunished. The March 2004 riots targeting Serbs, Roma, Ashkali and Egyptians - which began in Mitrovica - also remain under-investigated and under-prosecuted.

The EU mission in Kosovo, Eulex, is focused on the rule of law, because of a recognition in Brussels that the justice system is Kosovo's weakest institution. But like those of its UN predecessor, the efforts of the EU mission to help deliver justice for the most serious crimes have yet to deliver strong results.

This lack of progress can be attributed in part to a lack of political will to treat as priorities these politically charged and sensitive cases and the systemic weaknesses of the Kosovo justice system. Witness protection is a particular weakness. Relocation outside Kosovo is the only solution in the most serious cases, yet the EU and other states remain reluctant to host such witnesses. And the lack of consensus among EU member states about Kosovo's status impedes the ability to agree on a common approach that could break the logjam.

The lack of consensus about Kosovo's status has also had a wider impact on the ability of Eulex to deliver its mandate. While the mission provides much-needed technical assistance, greater political support from the EU is needed if the mission and the Kosovo's justice system are going to be able to make progress against political violence. Strong EU pressure on Belgrade is also needed to ensure its co-operation on justice issues in Kosovo, particularly in the context of lawless Mitrovica.

The recent events in Mitrovica are a stark reminder that violence remains a political tool in Kosovo. It is clear that both crisis-response and long-term solutions must be found to strengthen the rule of law in all of Kosovo, and to signal that impunity for political violence will no longer be tolerated.