Russian President Vladimir Putin said Thursday that Moscow has no plans to send troops to shore up Venezuela’s embattled leader. He also warned that the U.S. reluctance to start talks on extending a key arms control pact raises the threat of an uncontrollable arms race.

Asked about U.S. President Donald Trump’s tweet earlier this week that Moscow had informed Washington it had pulled its personnel out of Venezuela, Putin said that Russian experts come and go to service Russian-made weapons bought by Caracas.

“We aren’t building any military bases there, we aren’t sending troops there, we have never done that,” Putin said. “But we have fulfilled our contract obligations in the sphere of military-technical cooperation and we will keep doing that.”

The Russian leader said the U.S. sanctions against Venezuela have hurt ordinary people and warned Washington against using force.

Russia has staunchly backed Venezuelan President Nicolas Maduro, while the U.S. and several dozen other nations have cast their support behind opposition leader Juan Guaido and recognized him as interim president, asserting that Maduro’s re-election last year was illegitimate.

Speaking at a meeting with international news agencies’ chiefs in St. Petersburg, Putin also issued a stern warning about the danger of a new arms race that could spin out of control.

He accused the United States of shunning talks on extending the New START nuclear arms reduction treaty that is set to expire in 2021.

Putin noted that while Russia has repeatedly signaled its intention to begin discussions on extending the pact, Washington has given no response.

“We have said a hundred of times already that we are ready, but no one is talking to us,” he said.

The pact that was signed in 2010 by U.S. President Barack Obama and Russian President Dmitry Medvedev limits each country to no more than 1,550 deployed nuclear warheads and 700 deployed missiles and bombers.

Putin also criticized the U.S. withdrawal from another key arms pact, the 1987 Intermediate-Range Nuclear Forces Treaty, rejecting Washington’s claims of Russian violations of the agreement.

Citing Russian violations, the U.S. has formally suspended its obligations under the INF that bans all land-based cruise and ballistic missiles with a range of 500 to 5,500 kilometers (310 to 3,410 miles), setting the stage for the treaty to terminate later this year. Russia, which has denied any breaches, has followed suit.