The United States sees value in the New START arms control treaty with Russia, despite Washington’s concerns about Moscow’s track record on arms control and other issues, senior U.S. officials said Friday.

The remarks by the Trump administration officials, speaking to reporters on condition of anonymity, suggest the treaty will remain in force and the door remains open to pursuing an extension of the accord, which is set to expire in 2021.

The New Strategic Arms Reduction Treaty gives both countries until February 2018 to reduce their deployed strategic nuclear warheads to no more than 1,550, the lowest level in decades. It also limits deployed land- and submarine-based missiles and nuclear-capable bombers.

Moscow seen as unreliable

Reuters has reported that President Donald Trump, in his first call with Russian President Vladimir Putin, criticized the New START treaty, saying it favored Moscow.

But one of the Trump administration officials said on Friday the United States was not looking to discard New START.

Senior U.S. officials, including U.S. Defense Secretary Jim Mattis, have questioned Russia’s reliability on arms control, citing longstanding U.S. allegations that Russia has violated the Cold War-era Intermediate-range Nuclear Forces (INF) Treaty. Russia denies treaty violations and accuses the United States of them.

Working to improve relations

The accusations come amid a nosedive in U.S.-Russian relations.

U.S. intelligence agencies accuse Russia of meddling in the U.S. presidential election, which Moscow denies, and recent tit-for-tat exchanges between Washington and Moscow include moves to slash each others’ diplomatic presence.

The tensions have reached Syria, where the United States and Russia are backing different forces that are scrambling to claim what is left of Islamic State-held territory.

Russia warned the United States on Thursday it would target U.S.-backed militias in Syria if Russian troops again came under fire.

Still, a second senior Trump administration official said Friday the United States was seeking ways to improve communication with Moscow and build some degree of trust, which the official described as nonexistent.

Trump took office saying he wanted to improve ties strained since Moscow’s 2014 annexation of Crimea and the separatist conflict in eastern Ukraine, which led Washington to impose sanctions on Russia.

Ukraine’s Petro Poroshenko met Trump on Thursday and said afterward that they had a shared vision of a “new level” of defense cooperation.

But the second senior Trump administration official said there had been no decision on whether to provide defensive arms to Ukraine, something Kiev has long wanted.