Calls are mounting among Western nations to allow attacks on Russian territory using weapons that they have sent the Ukrainian military, a measure that Ukraine says will enable it to better prevent Russian attacks.

On Monday, the NATO Parliamentary Assembly, made up of lawmakers from countries belonging to the military alliance, adopted a declaration urging NATO members to lift a ban on firing Western weapons into Russia. That came after similar calls by NATO’s top official, Jens Stoltenberg, and government ministers in Poland, Lithuania, Latvia and Sweden.

The calls to allow Ukraine to expand its use of the Western weapons are mostly directed at the United States, the largest supplier of arms to the Ukrainian government. Washington has repeatedly asked Ukraine not to fire U.S.-made weapons into Russian territory for fear of escalating the war, although a debate has now opened within the Biden administration over relaxing the ban.

Ukraine has complained in recent months that the ban allows Russian forces to launch attacks from inside Russian territory without risk and hampers its ability to repel them. That disadvantage became clear this month when Russia started a new offensive in northeastern Ukraine after amassing troops and equipment just across the border.

“We had information from our intelligence services about Russia accumulating troops on the other side of the border but we couldn’t strike them to prevent this offensive,” Yehor Cherniev, the deputy chairman of the Ukrainian Parliament’s national security committee, said in a phone interview. “We had to wait for when they crossed the border.” He added: “It cost us a lot of lives.”