BELGRADE (Reuters) - Serbia is ready to resume dialogue with Kosovo over the normalization of ties only after Pristina lifts import tariffs on Serbian goods imposed last year, President Aleksandar Vucic said in a letter to U.S. President Donald Trump on Thursday.

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Serbia and its former province of Kosovo committed in 2013 to an EU-sponsored dialogue meant to resolve all issues between them, but little progress has been made.

Kosovo, which has a mainly ethnic Albanian population, seceded from Serbia in 2008 after a 1999 war in which NATO struck Serbian forces accused of carrying out atrocities during a campaign against Kosovo rebels.

Relations between them worsened late last year when Kosovo imposed 100 percent import duties on Serbian goods. The move came in a response to Belgrade’s efforts to prevent Kosovo from joining international bodies including the United Nations.

On Dec 14, Trump sent letters both to Vucic and Kosovo leader Hashim Thaci, urging them to reach a deal.

Vucic, a former Serbian ultra-nationalist who has switched to a pro-Western stance, is committed to bringing Serbia into the European Union, which has demanded that Belgrade first resolve its differences with Kosovo.

The government of Vucic has been the target of weeks of street demonstrations from opponents, some of whom accuse him of selling out Serbia’s interests to join the West.

In the letter to Trump, Vucic said Kosovo import duties remained “a burden and an insurmountable obstacle for the continuation of the dialogue.”

Both the EU and United States have urged Kosovo to scrap import tariffs, but Pristina has so far refused.

“I want to stress ... that the very moment when Pristina annuls that senseless and damaging measure, we are ready to resume dialogue,” Vucic said in the letter to Trump.

Serbia, its allies Russia and China, as well as five EU member states remain opposed to Kosovo independence.

According to its Chamber of Commerce, Serbia could suffer around 250 million euros or around 0.7 percent of its gross domestic product in annual damage due to Kosovo import tariffs.

Vucic also invited Trump to be the first U.S. President to visit Serbia in more than 40 years.