Lithuania and its fellow Baltic states Latvia and Estonia -- all bordering Russia -- fear they could be next in Moscow's crosshairs were it to win its war against Ukraine.

All three countries have been ramping up their defences since Russia's invasion of Ukraine in 2022 and boosting their border security measures over what they allege was a Russia-inspired influx of migrants at the border.

The latest spending push would allow Lithuania to "block and slow down the actions of hostile states", the defence ministry said.

In January, Lithuania announced plans to spend an annual five to six percent of its GDP on defence from 2026 to 2030.

The ministry said "intensive" work was now ongoing to identify how to "ensure the integrity of the Baltic defensive line".

It said 800 million euros of the overall sum would be spent on anti-tank mines.

The Baltic states also joined Finland and Poland in deciding this year to leave the Ottawa Convention that bans acquiring, producing, stockpiling or using anti-personnel mines.

The mines, designed to be buried or hidden on the ground, often mutilate victims, who do not immediately die, and aid groups denounce their long-term impact on civilians.

Human rights groups, including Amnesty International and the International Committee of the Red Cross (ICRC), have condemned the decision to abandon the treaty.

As part of the planned measures, Lithuania will stockpile anti-tank systems and other fortifications near the so-called Suwalki Gap -- a corridor 70 kilometres (43 miles) wide that connects the Baltic states with Poland.

The narrow stretch of land is flanked by the Russian exclave of Kaliningrad on one side and by Moscow's ally Belarus on the other.

Lithuania plans to deepen irrigation ditches that could serve as trenches, reforest border areas and plant trees on key roads to protect civilians and the military.

Additional measures include "electronic warfare capabilities, anti-drone systems and the strengthening of the observation and early warning system", the ministry said.