WASHINGTON, June 3 (Reuters) - The United States does not believe it needs to increase the size of its own nuclear arsenal in order to deter the combined forces of Russia, China and other rivals, White House national security adviser Jake Sullivan said on Friday.

He also said the United States would abide by the nuclear weapons limits set in the New START treaty until its 2026 expiration if Russia does the same. Sullivan made the remarks in a speech in which he sought to coax Moscow and Beijing into arms control talks.

"The United States does not need to increase our nuclear forces to outnumber the combined total of our competitors in order to successfully deter them," Sullivan told the Arms Control Association, the oldest U.S. arms control advocacy group.

Russian President Vladimir Putin in February said Moscow was suspending participation in New START, the last remaining pact limiting U.S. and Russian strategic nuclear arms.

"While claiming to suspend New START, Russia has also publicly committed to adhere to the treaty's central limits, indicating a potential willingness to continue limiting strategic nuclear forces through 2026. We agree," Sullivan said.

"It is in neither of our countries’ interests to embark on an open-ended competition in strategic forces and we are prepared to stick to the central limits as long as Russia does,” he said. "Rather than waiting to resolve all of our bilateral differences, the United States is ready to engage Russia now to manage nuclear risks and develop a post-2026 arms control framework."