Several news sites in Kosovo re-run an opinion piece by Marc Champion originally published in Bloomberg View.

Eight years after Kosovo declared its independence from Serbia, five European Union states still refuse to recognize it. They need to relent. They are contributing to an economic and security sinkhole in the heart of the Balkans -- and if history is any guide, that's a bad idea.

During a chat with Kosovo's Prime Minister Isa Mustafa as he passed through the U.K. last week, it came up almost in passing that his country cannot join the EU's police information-sharing network, Europol, and is struggling to join Interpol. This is self-harm on the part of the countries doing the blocking.

I'm not saying Kosovo's secession from Serbia was a good thing. On the contrary, U.S. President George W. Bush's decision to endorse Kosovo's independence in 2008 was one of the worst he made -- a high bar. It made nonsense of the entire rationale based on which the international community intervened militarily in the former Yugoslavia: To prevent the change of borders by force. Russia took the Kosovo precedent and ran with it, starting in Georgia just months later.

But that is now history. Kosovo will not return to Serbia. More than half of all nations have recognized the former province as a state. In Europe, 80 percent have done so, and with good reason: Failure to integrate Kosovo will put their own security at risk.

Kosovo, a nation of 1.8 million, has Europe's highest proportion of citizens fighting with jihadists in Syria and Iraq; 232 as of a year ago and no doubt more today. Cross-border organized crime is entrenched, aided by corruption and in some cases complicity at high levels. So it makes no sense to leave this link in Europe's intelligence and information chain dark. Here's how Mustafa put it:

People went to Syria and Iraq and we have to prepare to deal with the consequences when they come back. For that we need regional cooperation, and we need access to international organizations such as Interpol. But for us the entry process has been prolonged.

For Europol the holdup is the five EU members that haven't recognized Kosovo as a country: Cyprus, Greece, Romania, Slovakia and Spain. For Interpol, the problem is wider:

At the international level, Russia and China make problems for us through the Security Council, and then other countries side with them. The same is true for UNESCO membership.

Russia is hardly about to change its mind on this -- at least not until the rest of the world recognizes Crimea as Russian and the Russian-occupied Georgian territories of Abkhazia and South Ossetia as independent. So probably never. What matters most, though, is something Russia can't block: integrating Kosovo into EU programs and structures.

There may not be unlimited time to get this right. Nationalists are growing stronger in the Balkans as elsewhere in Europe. In Kosovo, they have gelled in the Self-Determination party, which is demanding that Mustafa's government resign over its acceptance of an EU-brokered agreement that gives limited autonomy to Kosovo's ethnic Serbs in an area close to the Serbian border. They are furious, too, over the government's agreement to settle the border between Kosovo and Montenegro. Opposition legislators have repeatedly released tear gas in parliament:

When we regional prime ministers speak with each other, we all talk about the rise of nationalist tendencies that we see. We have to be very careful not to let that take over.

Populist appeals are striking a nerve. Unemployment in Kosovo is 35 percent, and a staggering 61 percent among people under 25. Kosovo has become the poorest corner of the Balkans, in part because it has become so isolated in terms of trade, investment and travel. This in turn has driven hundreds of thousands of Kosovars to look for work abroad -- in the EU.

Mustafa was in London to meet with the European Bank for Reconstruction and Development, which is helping with construction of a highway to Serbia and with upgrading the railway that links Serbia, Kosovo and Macedonia. He also wants to apply for membership in the World Trade Organization, but that may prove impossible because it is subject to a vote by current WTO member states.

Recently, Kosovo sought to join UNESCO, the United Nations heritage protection organization. Russia helped Serbia block the bid and Kosovo fell three votes short of the two-thirds majority it needed. Kosovo's population may be more than 90 percent ethnic Albanian, but many of the ancient sites in need of upkeep and protection are Serbian Orthodox Churches.

It is hard to imagine Spain, which has so mishandled its own separatist movement in Catalonia, giving way to a unilateral secession by Kosovo, even now. At a minimum, though, Spain and Serbia's other EU friends can stop blocking Kosovo's membership in vital organizations. There is more to lose than symbolism.