NATO Secretary General Jens Stoltenberg said last week that most members of the alliance support Ukrainian forces conducting air strikes in Russia.

Ukraine is currently expected to receive F-16 fighter jets this summer, with as many as twelve pilots trained to fly the aircraft. Stoltenberg remarked in an interview that the allies will likely not restrict the use of the jets in conducting strikes on Russian targets in their territory.

“Different allies have slightly different policies on this,” he said in a translation of the interview. “This is Russia's armed aggression against Ukraine in gross violation of international law, and according to international law, Ukraine has the right to self-defense. This also includes striking legitimate military targets: Russian military targets outside of Ukraine. This is international law.”

Stoltenberg added that the allies need to ensure the presence of “the maintenance, the staff, and all the support systems” before the F-16s are delivered to Ukraine.

“I think we have to listen to the military experts exactly when we will be ready to or when allies will be ready to start sending and delivering the F-16s,” the former prime minister of Norway said. “The sooner, the better. At the same time, it has to be effective weapons with well-trained pilots, with good support systems available when we provide this mechanism to Ukraine.”

The approval from Western allies for Ukraine to conduct strikes in Russia comes weeks after the former nation used drones to attack refineries, gunpowder factories, and arms producers in the latter nation. The Russian city of Belgorod was barraged with missiles at the end of last year.

The United States has supported Ukraine with $113 billion in military and humanitarian funds since Russian forces invaded the country two years ago, according to an analysis from the Center for Strategic and International Studies. Another analysis from the Council of Foreign Relations found that the United States has provided more assistance to Ukraine than any other nation except for European Union institutions, which have primarily offered financial aid.

Members of the Senate recently passed a $95 billion package that includes $60 billion in aid for Ukraine, as well as $14 billion for Israel. Controversial efforts claiming to increase security measures at the southern border were removed from the deal.