WASHINGTON — The White House disputed a report Thursday that President Trump was unaware of a U.S.-Russia nuclear arms treaty during a phone call with Russian President Vladimir Putin.

White House press secretary Sean Spicer said Trump paused in the call because he was “seeking an opinion” from advisers.

Reuters reported that Trump had stopped to ask aides what the New START treaty was. Spicer said that Trump was aware of the treaty that was forged during the previous administration.

Signed by Russia and the U.S. in 2010, the New START treaty limits nuclear arsenals to no more than 1,550 deployed nuclear warheads for each country. The treaty is due to expire in 2021, but it could be extended because both countries appreciate the measure of transparency the deal offers.

As a candidate, Trump was critical of the agreement, which set new, lower caps on the number of nuclear warheads each country can have.

There have been frictions regarding another arms control pact, the 1987 Intermediate-Range Nuclear Forces Treaty, which outlawed that entire class of nuclear missiles. Washington and Moscow have traded mutual accusations of violating the treaty.

In December, Trump said on Twitter that the U.S. should “greatly strengthen and expand its nuclear capability” until the rest of the world “comes to its senses” regarding nuclear weapons.