MOSCOW -- Russian President Vladimir Putin says there is no need for a Russia-China military alliance now, but noted it could be forged in the future.

Putin's statement signalled deepening ties between Moscow and Beijing amid growing tensions in their relations with the United States. The Russian leader also made a strong call for extending the last remaining arms control pact between Moscow and Washington.

Asked during a video conference with international foreign policy experts Thursday if a military union between Moscow and Beijing was possible, Putin replied that "we don't need it, but, theoretically, it's quite possible to imagine it."

Russia and China have hailed their "strategic partnership," but so far rejected any talk about the possibility of their forming a military alliance.

Putin pointed to the war games that the armed forces of China and Russia held as a signal of the countries' burgeoning military co-operation.

Putin also noted that Russia has shared sensitive military technologies that helped significantly boost China's military potential, but didn't mention any specifics, saying the information was sensitive.

"Without any doubt, our co-operation with China is bolstering the defence capability of China's army," he said, adding that the future could see even closer military ties between the two countries.

"The time will show how it will develop, but we won't exclude it," the Russian president said.

Russia has sought to develop stronger ties with China as its relations with the West sank to post-Cold War lows over Moscow's annexation of Ukraine's Crimea, accusations of Russian meddling in the 2016 U.S. presidential election and other rifts.

Putin on Thursday emphasized the importance of extending the New START treaty that expires in February, Russia's last arms control pact with the United States.

Earlier this week, the United States and Russia signalled their readiness to accept compromises to salvage the New START treaty just two weeks ahead of the U.S. presidential election in which President Donald Trump faces a strong challenge from former Vice-President Joe Biden, whose campaign has accused Trump of being soft on Russia.

New START was signed in 2010 by then-U.S. President Barack Obama and then-Russian President Dmitry Medvedev. The pact limits each country to no more than 1,550 deployed nuclear warheads and 700 deployed missiles and bombers, and envisages sweeping on-site inspections to verify compliance.

Russia had offered to extend the pact without any conditions, while the Trump administration initially insisted that it could only be renewed if China agreed to join. China has refused to consider the idea. The U.S. recently modified its stance and proposed a one-year extension of the treaty, but said it must be coupled with the imposition of a broader cap on nuclear warheads.

The Kremlin initially resisted Washington's demand, but its position shifted this week with the Russian Foreign Ministry stating that Moscow can accept a freeze on warheads if the U.S. agrees to put forward no additional demands.

Putin didn't address the issue of the freeze on warheads, but he emphasized the importance of salvaging New START.

"The question is whether to keep the existing treaty as it is, begin a detailed discussion and try to reach a compromise in a year or lose that treaty altogether, leaving ourselves, Russia and the United States, along with the rest of the world, without any agreement restricting an arms race," he said. "I believe the second option is much worse."

At the same time, he added that Russia "wasn't clinging to the treaty" and will ensure its security without it. He pointed at Russia's perceived edge in hypersonic weapons and indicated a readiness to include them in a future pact.

"If our partners decide that they don't need it, well, so be it, we can't stop them," he said. "Russia's security will not be hurt, particularly because we have the most advanced weapons systems."