US President Donald Trump signed a law on the US defence budget for the next year which was adopted by Congress. Among other things, it includes a call to change the mandate of NATO's Baltic Air Policing mission to that of an air defence mission.

The law states that the American political and military leadership should "explore transitioning the Baltic Air Policing mission of NATO to a Baltic air defence mission."

Lithuanian officials have raised this issue during meetings with allies for several years now, seeking to plug one of the largest military loopholes.

The air policing mission's transition to an air defence mission would mean that fighter jets stationed in the Baltics for the mission would be able to carry out combat tasks in case of a crisis.

The Baltic states do not have fighter jets of their own. They have short-range air defence systems and are in the process of purchasing medium-range air defence systems, but cannot afford long-range missile systems such as the Patriot.

NATO has been carrying out the Baltic Air Policing mission since 2004, when Estonia, Latvia and Lithuania joined the alliance.

The new law signed by Trump also includes a call for lawmakers to continue supporting the Baltic states. The document said such support should include the "continuous and enduring presence of United States forces, training and support activities of United States special operations forces, and increased joint training and exercises to deter aggression, promote interoperability, build resilience, and enable NATO to take collective action if required."

A company of American troops was stationed in each of the three Baltic states from 2014, when Russia annexed Crimea, until autumn 2017, but the US troops were withdrawn after international NATO battalions were established in Estonia, Latvia and Lithuania.

American troops now come to the Baltics for training from their brigade base in Poland.