The United States on Tuesday officially designated Pakistan's Balochistan Liberation Army (BLA) and its armed wing, the Majeed Brigade, as Foreign Terrorist Organizations (FTO).

Washington said the group is responsible for deadly attacks in Balochistan, including a train hijacking in March that killed 31 people.

"Today's action taken by the Department of State demonstrates the Trump administration's commitment to countering terrorism," Secretary of State Marco Rubio said in a statement.

Pakistan welcomed the designation on Tuesday.

What's behind the violence in Balochistan?

Balochistan is Pakistan's largest but least populated province, home to the Sunni Muslim ethnic minority known as the Baloch.

Separatists have fought since the early 2000s for autonomy and a greater share of the region's rich natural resources. The Baloch Liberation Army (BLA) is the largest militant group operating in the province.

In March, the BLA claimed responsibility for an attack on a train traveling from Quetta to Peshawar, killing 31 civilians and security personnel and holding more than 300 passengers hostage.

Pakistan says it has quelled the insurgency, but violence continues in Balochistan. Troops killed 50 militants in the Zhob district over the past week, according to the military.

On Monday, at least nine Pakistani soldiers were killed when dozens of militants attacked a police station and border force compound in southwestern Balochistan.

"Pakistan remains a steadfast bulwark against terrorism. Our sacrifices have secured critical counterterrorism successes, not only for the country, but for regional stability and global security," Pakistan's Ministry of Foreign Affairs said in a statement.

Why is the US focusing on the BLA now?

The US first labeled the BLA a terrorist group in 2019. Now, it has formally designated the group as a Foreign Terrorist Organization — a move analysts say will tighten scrutiny of its supporters in the US and Europe.

The designation coincides with a visit to Washington by Pakistan's army chief, Field Marshal Asim Munir. It also comes less than two weeks after the US and Pakistan signed a trade agreement expected to allow American firms to help develop Pakistan's largely untapped oil reserves in resource-rich Balochistan.

Separatists in Balochistan have opposed the extraction of resources by Pakistani and foreign firms and have targeted Pakistani security forces and Chinese nationals working on multibillion-dollar projects.

Edited by: Dmytro Hubenko