President Joe Biden and Vladimir Putin were still far apart after two hours of talks on the escalating crisis caused by Russia’s massing of tens of thousands of troops near its border with Ukraine.

Biden delivered a simple message during Tuesday’s video call with Putin: invade Ukraine again and face painful sanctions that will do resounding harm to your economy. Putin had his own blunt take, according to his foreign adviser Yuri Ushakov, telling the U.S. president that “the Russian troops are on their own territory, and they don’t threaten anyone.”

With no immediate breakthrough to ease tensions on the Ukraine question, the U.S. emphasized a need for diplomacy and de-escalation, while issuing stern threats to Russia about the high costs of a military incursion.

"President Biden reiterated his support for Ukraine’s sovereignty and territorial integrity and called for de-escalation and a return to diplomacy," it went on.

Putin demands 'guarantees' on NATO expansion

According to the readout released by the Kremlin after the talks, Putin demanded guarantees that ex-Soviet Ukraine would not join NATO in the future.

"Russia is seriously interested in obtaining reliable, legally fixed guarantees that rule out NATO expansion eastward and the deployment of offensive strike weapons systems in states adjacent to Russia," the Kremlin said.

Putin also demanded guarantees that offensive strike systems would not be deployed in countries neighbouring Russia, according to the Kremlin readout.

Biden gave no commitments to Putin on over any demand for Ukraine to be blocked from joining NATO or for a reduced US military presence in the region, Sullivan told reporters after the summit.