The White House has expressed concern over an "unprecedented" buildup of Serbian troops and military equipment along the Kosovo border 

NATO's peacekeeping force in Kosovo, Kfor, has received reinforcements from British troops 

The Biden administration is consulting with allies to ensure Kfor's readiness matches the perceived threat posed by the Serbian military buildup 

The US National Security Council's spokesperson, John Kirby, reported the presence of advanced Serbian artillery, tanks, and mechanized infantry units near the Kosovo border 

The situation is considered highly destabilizing, and the US has called on Serbia to withdraw its forces from the border to reduce tensions 

National Security Adviser Jake Sullivan discussed the escalation with Kosovan Prime Minister Albin Kurti 

Secretary of State Antony Blinken urged immediate de-escalation and a return to previous agreements to normalize relations with Kosovo when speaking with Serbian President Aleksandar Vučić 

The tension began with an ambush on a Kosovan police patrol by well-armed Serb paramilitaries, resulting in casualties on both sides 

The Kosovan government produced evidence suggesting that the Serbian army may have supplied weapons to the paramilitary group 

There are concerns that the Serbian military buildup could lead to conflict and erode the sovereignty of Kosovo, potentially affecting the region's security and stability