"We've addressed a possibility of reciprocal transparency measures with the Russian government, including on offensive weapons and systems in Ukraine as well as measures to increase confidence regarding military exercises in Europe," Sullivan told an online briefing.
According to him, these ideas "have a potential to enhance our security and of our allies" and address Russia's concerns.
Sullivan expects that after Russia studies the US written response, there will be further diplomatic engagements.
"[I hope] there would be a discussion, phone conversation, meeting, I don't know, it has not been agreed to," he said.
The US ambassador has described relations with Russia as "pretty bleak" and did not rule out their further deterioration over Ukraine tensions.
"Diplomatic relations [between the US and Russia] are at a low point now, but I feel pretty confident in saying that there would be any further significant blow to what is already a pretty bleak diplomatic situation in relations between the United States and Russia," Sullivan told an online briefing.
The diplomat insisted that a "Russian threat" to Ukraine is "very imminent." However, Kiev itself has repeatedly downplayed the alleged risk of an "imminent Russian invasion."
Tensions around Ukraine have intensified over the past several months after Russia was accused of a troop build-up near the Ukrainian border and allegedly preparing for an invasion. Moscow has denied these accusations, pointing to NATO's military activity near Russian borders, which it deems a threat to its national security.
Sullivan also touched upon the lack of diplomatic staff at the US embassy in Moscow.
"...there are many issues that we need to engage with the Russian government on, we would be in a much better position to do so if we had a stronger diplomatic platform here, but we're continuing to work on those [issues] with the Russian government," the ambassador said.
He noted that there continue to be topics under discussion between Russia and the United States.
He noted that there continue to be topics under discussion between Russia and the United States.
"We continue to have the New START treaty, strategic stability dialogue, cyber dialogue, the JCPOA [Iran nuclear deal]," Sullivan said.
Last April, Moscow banned the US embassy from hiring Russian and third-country nationals. The move came after the US imposed sanctions on 32 Russian entities and individuals over alleged cyberattacks and other hostile acts, and ordered 10 Russian diplomats out. A month after the ban, Sullivan said the US embassy would be unable to provide full consular services starting 1 August.
Last April, Moscow banned the US embassy from hiring Russian and third-country nationals. The move came after the US imposed sanctions on 32 Russian entities and individuals over alleged cyberattacks and other hostile acts, and ordered 10 Russian diplomats out. A month after the ban, Sullivan said the US embassy would be unable to provide full consular services starting 1 August.